Question

The radius of a Hillstone varies directly with amount of time that it was in a club after a Hillstone has been in particular cloud for 10 seconds it’s radius was 0.5 inches how long would it have to be in the cloud to have a radius of 1.25 inches

Answer 1

Let the radius be r and the time be t.

As per condition, r is proportional to t.

$r=kt$

Now it is given that for r=0.5, t=10, so it follows:

$\begin{gathered} 0.5=k(10) \\ k=0.05 \end{gathered}$

So the equation becomes:

$r=0.05t$

Here r is in inches and t is in seconds.

For r=1.25, the value of t is:

$\begin{gathered} 1.25=0.05t \\ t=\frac{1.25}{0.05} \\ t=25 \end{gathered}$

So the value of t is 25 seconds.