Test Index

JAMB Mathematics 2013 Paper

Question : 13

Total: 47

Solution:

Concept:

Joint inverse variation can be expressed as a single equation using a constant of proportionality.

Explanation:

Since

r

varies inversely as

\sqrt{s}

and

\sqrt{t}

, write:

r \propto \frac{1}{\sqrt{s}}

and

r \propto \frac{1}{\sqrt{t}}

Combining them gives

r = \frac{k}{\sqrt{s}\sqrt{t}} = \frac{k}{\sqrt{st}}

Rearranging:

\sqrt{st} = \frac{k}{r}

Square both sides:

st = \frac{k^2}{r^2}

Divide through by

t

s = \frac{k^2}{r^2 t}

Hence,

s

varies inversely as

r^2

and

t

Answer:

B. s varies inversely as

r^{2}

and

t

Go to Question:

Prev Question

Next Question