Question

If x varies inversely as y and x = 30 when y = 12, find y when x = 15.
A. y = 35
B. y = 24
C. y = 6
D. y = 14

Answer 1

So \(\mathbf{y = k{1 \over x}}\) is the formula.

\( \color{Black}{\Rightarrow 12 = k{1 \over 30} }\)

Multiplying both sides by 30.

\( \color{Black}{\Rightarrow 360 = k }\)

We know that the certain constant 'k' is 360.

\( \color{Black}{\Rightarrow y = 360 \times {1 \over 15}}\)

\( \color{Black}{\Rightarrow y = 24 }\)