SAT Math Question of the Day

Math Category: Fractions Level 2:

Q: If 1/z2 = 4/25, then what is z?

  1. 2/5
  2. 4/25
  3. 3/2
  4. 5/2
  5. 25/4

UNANSWERED.

The correct answer is D.

A: The answer is 5/2.

1/z2 = 4/25
Cross-multiply
1 × 25 = z2 × 4
25 = 4z2
z2 = 25/4
Take the square root of both sides
z = √ (25/4)  = √ 25  / √ 4  = 5/2