Question

M is inversely proportional to r if m= 9 when r= 4 find m when r=2

Answer 1

m=18 when r = 2.

Step-by-step explanation:

Given,

m∝$\frac{1}{r}$

So,

m = k×$\frac{1}{r}$,--------eq 1, here k is the constant.

To find the value of m when r = 2

At first we need to find the value of k

Solution

Now,

Putting the values of m=9 and r = 4 in eq 1 we get,

9 = $\frac{k}{4}$

or, k = 36

So, eq 1 can be written as m= $\frac{36}{r}$

Now, we put r =2

m = $\frac{36}{2}$

or, m= 18

Hence,

m=18 when r = 2.