Mathematics Flashcards

Solve for x: 3x − 7 = 14

Answer: x = 7

Add 7 to both sides to get 3x = 21, then divide by 3 to get x = 7.

A circle has a radius of 5 cm. What is its circumference? (Use π ≈ 3.14)

Answer: 31.40 cm

Circumference = 2πr = 2 × 3.14 × 5 = 31.40 cm.

Which number is NOT a prime number?

Answer: 21

21 = 3 × 7, so it has factors other than 1 and itself, making it composite.

What is 15% of 200?

Answer: 30

15% of 200 = 0.15 × 200 = 30.

A bag contains 3 red, 5 blue, and 2 green marbles. What is the probability of randomly picking a blue marble?

Answer: 1/2

There are 5 blue marbles out of 10 total, so P = 5/10 = 1/2.

Which expression represents 'four more than twice a number n'?

Answer: 2n + 4

'Twice a number n' is 2n, and 'four more than' means adding 4, giving 2n + 4.

Two angles are supplementary. One angle measures 65°. What is the measure of the other angle?

Answer: 115°

Supplementary angles add to 180°, so the other angle = 180° − 65° = 115°.