Digital SAT Math Practice Flashcards

A car travels 240 miles in 4 hours at a constant speed. At this rate, how many miles will it travel in 7 hours?

Answer: 420

The speed is 240/4 = 60 mph; in 7 hours it covers 60 × 7 = 420 miles.

If the system of equations y = 2x + 1 and y = −x + 7 is graphed, at which point do the lines intersect?

Answer: (2, 5)

Setting 2x + 1 = −x + 7 gives 3x = 6, x = 2; substituting back yields y = 5.

The population of a town doubles every 10 years. If the population is currently 5,000, what will it be in 20 years?

Answer: 20,000

After 10 years the population is 10,000; after 20 years it doubles again to 20,000.

A circle has a radius of 5. What is the area of the circle in terms of π?

Answer: 25π

Area = πr² = π(5)² = 25π.

If f(x) = 3x² + 2x − 1, what is the value of f(−1)?

Answer: 0

f(−1) = 3(1) + 2(−1) − 1 = 3 − 2 − 1 = 0.

A bag contains 4 red marbles, 6 blue marbles, and 2 green marbles. If one marble is drawn at random, what is the probability it is NOT blue?

Answer: ½

There are 12 total marbles; 6 are not blue (4 red + 2 green), so P(not blue) = 6/12 = 1/2.

What value of x satisfies the equation √(2x + 6) = 4?

Answer: 5

Squaring both sides: 2x + 6 = 16, so 2x = 10 and x = 5.