Preguntas de práctica ACT
Las preguntas del test siguen en inglés.
Esta es una muestra gratis de 15 preguntas de ACT que puedes hacer aquí mismo, con las cuatro áreas mezcladas más o menos en las proporciones que usa el examen: English, math, reading y science. Combina opción múltiple, marcar todas las que correspondan y completar huecos, y cada pregunta trae explicación. Responde las 15, después mira tu puntuación y lee por qué funciona cada respuesta.
Which version of the sentence is punctuated correctly?
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Las 15 preguntas de un vistazo
¿Prefieres leer antes de jugar? Abajo están todas las preguntas de la muestra. Las respuestas y explicaciones quedan plegadas hasta que las abras.
1. Which version of the sentence is punctuated correctly?
- A. The storm knocked out power for two days, we cooked everything on a camp stove.
- B. The storm knocked out power for two days; we cooked everything on a camp stove.
- C. The storm knocked out power for two days we cooked everything on a camp stove.
- D. The storm knocked out power for two days, and, we cooked everything on a camp stove.
Ver respuesta y explicación
Respuesta: B. The storm knocked out power for two days; we cooked everything on a camp stove.
Both halves of this sentence can stand alone, so joining them with only a comma creates a comma splice. Two independent clauses need a semicolon, a period, or a comma followed by a joining word such as and or so.
2. Complete the sentence.
The box of old photographs that my grandparents kept in the attic _____ finally been opened.
Opciones para el hueco 1: have, has, having, were
Ver respuesta y explicación
Respuesta: has
The subject is box, which is singular, so the verb is has. The ACT often buries the subject by putting a prepositional phrase and a relative clause between it and the verb, so find the subject before you decide on the verb form.
3. A paragraph reads: In its first year, the school's bike repair club fixed 140 bicycles for students who would otherwise have paid a shop. The writer wants to end the paragraph with a sentence that supports its point about saving students money. Which choice does that best?
- A. A basic tune-up at a local shop starts at about forty dollars, so the club kept thousands of dollars in students' pockets.
- B. The club meets on Tuesdays in the shop room behind the gym.
- C. Bicycles have been a common way to get around the city for decades.
- D. Two members of the club later joined the track team.
Ver respuesta y explicación
Respuesta: A. A basic tune-up at a local shop starts at about forty dollars, so the club kept thousands of dollars in students' pockets.
Rhetorical skills questions are decided by the purpose stated in the question, not by which sentence sounds nicest. Only the first choice puts a number on the money saved, while the others are true sounding details that never touch cost.
4. Which of these sentences use an apostrophe correctly?
Marca todas las que correspondan.
- A. The team celebrated its first win in three years.
- B. It's been a long season for the coaching staff.
- C. Both players' jerseys were retired on the same night.
- D. The bus left without it's driver.
- E. The Wilsons' invited us to dinner.
Ver respuesta y explicación
Respuesta: A. The team celebrated its first win in three years., B. It's been a long season for the coaching staff., C. Both players' jerseys were retired on the same night.
Its is the possessive form and takes no apostrophe, while it's is only ever a contraction of it is or it has. A plural that already ends in s takes the apostrophe after the s, as in players' jerseys, and a plain plural family name like the Wilsons takes no apostrophe at all.
5. A jacket is marked down 30 percent, and the sale price is $84. What was the original price?
- A. $109.20
- B. $114.00
- C. $120.00
- D. $126.00
Ver respuesta y explicación
Respuesta: C. $120.00
A 30 percent discount leaves 70 percent of the original price, so solve 0.7x = 84 and get x = 120. Adding 30 percent back onto the sale price gives $109.20, which is the trap answer, because the percent was taken from the larger number.
6. What is the slope of the line that passes through the points (-2, 5) and (4, -7)?
- A. -2
- B. -1/2
- C. 1/2
- D. 2
Ver respuesta y explicación
Respuesta: A. -2
Slope is the change in y over the change in x, so (-7 - 5) divided by (4 - (-2)) gives -12 over 6, which is -2. Watch the signs in the denominator, since subtracting a negative x value is the most common place this goes wrong.
7. Complete the sentence.
In a right triangle, the leg opposite angle A measures 5 and the hypotenuse measures 13, so sin A equals _____.
Opciones para el hueco 1: 5/12, 5/13, 12/13, 13/5
Ver respuesta y explicación
Respuesta: 5/13
Sine is the opposite side over the hypotenuse, which is 5 over 13. The third side is 12 by the Pythagorean theorem, so 12/13 is cos A and 5/12 is tan A, and those are the choices that catch people who mix up the three ratios.
8. Which of the following values are solutions to the equation x squared minus x minus 6 equals 0?
Marca todas las que correspondan.
- A. -3
- B. -2
- C. 0
- D. 2
- E. 3
Ver respuesta y explicación
Respuesta: B. -2, E. 3
The expression factors into (x - 3)(x + 2), so the solutions are 3 and -2. Checking beats trusting the factoring: 9 minus 3 minus 6 is 0, and 4 plus 2 minus 6 is 0, while -3 gives 9 plus 3 minus 6, which is 6.
9. Read the passage. When the Millbrook library ran out of shelf space, the head librarian did something odd with the empty basement room: she filled it with hammers, drills and a tile saw. Patrons could borrow a tool for a week the same way they borrowed a novel. Within two years the tool collection was checked out more often than the fiction shelves. Some staff were skeptical, and the repair bills were real, but the librarian argued that a library lends access, and access does not have to come in the shape of a book. The main idea of the passage is that:
- A. the Millbrook library had run out of shelf space.
- B. libraries should spend less money on fiction.
- C. one library widened what lending can mean, drawing doubts from staff but clear demand from patrons.
- D. most people find tools more useful than novels.
Ver respuesta y explicación
Respuesta: C. one library widened what lending can mean, drawing doubts from staff but clear demand from patrons.
A main idea has to cover the whole passage, not one sentence of it. The shelf space problem is only the setup, and the last two choices are broad claims about libraries and readers in general that this passage never makes.
10. Passage A: Rewilding a river means taking out what we built and stepping back. When the Corbin Dam came down, the channel rearranged itself in a single spring flood, and the fish returned without anyone stocking them. Nature keeps a blueprint we cannot draw. Passage B: Taking out a dam is not stepping back, it is one more decision. Someone picks which structure goes, which floodplain gets bought, and who pays for it. Rivers do recover, but calling that recovery natural hides the engineering and the money behind it. Both authors would most likely agree that:
- A. a river can recover ecologically after a dam is removed.
- B. people should stop managing rivers.
- C. dam removal costs too much to be worth doing.
- D. fish populations return only when they are restocked.
Ver respuesta y explicación
Respuesta: A. a river can recover ecologically after a dam is removed.
Paired passage questions ask you to find the narrow patch of common ground, not the argument. Passage A says the fish came back on their own and passage B says rivers do recover, so the two disagree about what to call the recovery rather than about whether it happens.
11. Complete the sentence.
Marisol read the committee's letter twice, set it down, and spent the rest of the afternoon rearranging books that were already in order. The narrator most likely wants readers to understand that Marisol is _____ the news in the letter.
Opciones para el hueco 1: indifferent to, unsettled by, delighted by, confused by the wording of
Ver respuesta y explicación
Respuesta: unsettled by
Inference questions ask what the details imply, and here the rereading plus the pointless busywork signal agitation the narrator never names outright. Indifference is ruled out by the second reading, and nothing in the scene suggests pleasure or trouble understanding the words.
12. A student dropped one tablet of compound Z into 200 mL of water and timed how long it took to dissolve completely, repeating the trial at four water temperatures. Trial 1: 10 degrees C, 96 seconds. Trial 2: 20 degrees C, 62 seconds. Trial 3: 30 degrees C, 41 seconds. Trial 4: 40 degrees C, 28 seconds. Based on these results, a tablet dropped into water at 25 degrees C would most likely take about how long to dissolve?
- A. 24 seconds
- B. 35 seconds
- C. 51 seconds
- D. 70 seconds
Ver respuesta y explicación
Respuesta: C. 51 seconds
25 degrees falls between trial 2 and trial 3, so the dissolving time falls between 62 and 41 seconds, and 51 seconds is the only choice in that range. Notice that you never needed to know what compound Z is, which is the point: the science section is a data reading test, and it often uses substances and setups you have never met.
13. A student wants to test whether adding salt changes how long water takes to freeze. Which of the following should be kept the same in every trial?
Marca todas las que correspondan.
- A. The starting temperature of the water
- B. The volume of water in each container
- C. The freezer setting
- D. The amount of salt added
- E. The time each sample takes to freeze
Ver respuesta y explicación
Respuesta: A. The starting temperature of the water, B. The volume of water in each container, C. The freezer setting
Everything except the one variable you are testing has to be held constant, or you cannot tell what caused a difference. The amount of salt is the variable being changed on purpose, and the freezing time is the result being measured, so neither one can be controlled.
14. Two scientists explain why dissolved oxygen in a lake has fallen. Scientist 1 says fertilizer running off nearby fields feeds algae, and the algae die and decay, which uses up oxygen. Scientist 2 says the lake water has warmed, and warmer water holds less dissolved oxygen. Which finding, if confirmed, would most weaken Scientist 2's explanation?
- A. Lake water temperature rose by 3 degrees C over the same period.
- B. Oxygen fell just as sharply in a nearby lake whose temperature did not change.
- C. Algae counts in the lake rose over the same period.
- D. Cold water is able to hold more dissolved oxygen than warm water.
Ver respuesta y explicación
Respuesta: B. Oxygen fell just as sharply in a nearby lake whose temperature did not change.
A case where the effect appears without the proposed cause is the strongest evidence against that cause, so an unwarmed lake losing oxygen just as fast undermines the temperature explanation. Rising algae counts support Scientist 1 without weakening Scientist 2, because both processes could be draining oxygen at once.
15. Figure 1 plots the size of two bacterial cultures over 8 hours. Culture A rises in a straight line from 200 cells per mL at hour 0 to 1,000 cells per mL at hour 8. Culture B holds steady at 800 cells per mL through hour 4, then falls in a straight line to 400 cells per mL at hour 8. According to Figure 1, at about what time are the two cultures the same size?
- A. Hour 2
- B. Hour 4
- C. Hour 5
- D. Hour 7
Ver respuesta y explicación
Respuesta: C. Hour 5
Culture A gains 100 cells per mL each hour, so it sits at 700 at hour 5, and culture B loses 100 per hour after hour 4, so it is also at 700 at hour 5. When a question asks when two things are equal, look for where the lines cross rather than reading each line on its own.
Qué entra de verdad en el ACT
El ACT es un examen de opción múltiple construido con cuatro áreas: English, math, reading y science. Cada sección que haces se puntúa en una escala de 1 a 36, y tu composite es la media de esas puntuaciones de sección, redondeada. Hay un ensayo opcional, puntuado aparte en su propia escala, que no cambia el composite. No se resta nada por fallar, así que nunca hay motivo para dejar una pregunta en blanco.
El formato está cambiando, y ahora mismo eso importa más de lo normal. Desde 2025 ACT empezó a desplegar una versión más corta del examen: menos preguntas, más tiempo por pregunta y science como sección opcional en vez de obligatoria. En esa versión el composite sale de English, math y reading, y la puntuación de science se informa aparte si eliges hacerla. Qué versión te toca puede depender de tu fecha de examen y de si te examinas online o en papel, así que trata cualquier número fijo de preguntas que leas en cualquier sitio, incluido un libro de preparación viejo e incluida esta página, como algo que hay que confirmar. Consulta el formato oficial del ACT para tu propia fecha de examen antes de montar un plan de ritmo sobre un número.
Lo que pide cada sección ha sido más estable que los recuentos. English evalúa uso y mecánica, o sea puntuación, gramática y estructura de la oración, más habilidades retóricas, o sea organización, estilo y si una frase pinta algo en el párrafo. Math va desde prealgebra y álgebra elemental hasta geometría analítica, geometría plana y algo de trigonometría. Reading se basa en textos: idea principal, detalle de apoyo, inferencia, vocabulario en contexto y preguntas que comparan dos textos sobre un mismo tema. Science te pone tablas, gráficos y explicaciones enfrentadas y te pide leerlas.
Cómo usar esta muestra
Estas 15 preguntas siguen en pequeño la mezcla de contenidos del ACT. English se lleva la parte mayor porque es la que más preguntas tiene en el examen real, math va después, y reading y science completan el resto. El ACT real es de opción múltiple de principio a fin. Esta muestra también usa marcar todas las que correspondan y completar huecos, porque en esos formatos es más difícil acertar adivinando, y por eso comprueban mejor si de verdad te sabes la regla.
Hazla de una sentada, sin apuntes y sin calculadora. El ACT premia la velocidad más que la mayoría de exámenes, y en el formato largo te dejaba bastante menos de un minuto por pregunta en varias secciones. El formato corto ha aliviado eso sin quitarlo, así que practicar a un ritmo en el que te comprometes con una respuesta y sigues vale tanto como repasar contenido.
Después lee la explicación de cada pregunta, también de las que acertaste. Una respuesta mal suele señalar una destreza y no un dato. Si fallaste la de la coma mal usada y la del apóstrofo, repasa la puntuación como un tema entero en vez de memorizar dos frases. Y fíjate en qué hiciste en las preguntas de science: si tiraste de algo que recuerdas a medias de clase de biología en vez de leer los números que tenías delante, ese hábito te va a costar puntos en el examen real.
Cómo StudyPDF crea tests completos con tu propio material
Quince preguntas te enseñan qué áreas flojean. Por sí solas no te preparan, y un conjunto de preguntas genérico no tiene ni idea de qué capítulos dio tu clase ni de qué errores repites.
StudyPDF va por otro camino, parte de tu material. Sube tu libro de preparación del ACT, tus apuntes de clase o un test de práctica que te devolvió tu profesor, y Bo, el agente de estudio, crea tests de práctica completos con esas páginas exactas. Cada pregunta sale de lo que subiste, y cada explicación remite a dónde estaba la respuesta, así que puedes comprobar la fuente cuando algo parezca mal. Puedes generar un test nuevo tantas veces como quieras, limitarlo a un área como la trigonometría o las reglas de la coma, y ver qué temas sigues fallando.
No necesitas ningún documento para empezar. También puedes decir solo un tema, por ejemplo interpretación de datos de ACT science o la concordancia entre sujeto y verbo, y Bo escribe un conjunto de práctica a partir de eso. Empezar es gratis.
Escrito por el equipo de StudyPDF. Actualizado el 2026-08-19.