Question

If y varies inversely as the square of x, and y = 1/8 when x = 1, find y when x = 5.

Answer 1

y = k / x² ( y varies inversely as the square of x )
y = 1/8 when x = 1:
1/8 = k / 1²
8 k = 1
k = 1/8
For x = 5:
y = 1/8 / 5² = 1/8 : 25 = 1/8 · 1/25 = 1/200
Answer: A ) 1/200