Question

If w varies jointly as x and y,
and w=10 when x=2 and y=1.
Solve for w when x=4 and y=2​

Answer 1

Given:

w varies jointly as x and y.

w=10 when x=2 and y=1.

To find:

The value of w when x=4 and y=2​.

Solution:

w varies jointly as x and y.

`w\propto xy`

`w=kxy` ...(i)

Where, k is the constant of proportionality.

w=10 when x=2 and y=1.

`10=k(2)(1)`

`10=2k`

`(10)/(2)=k`

`5=k`

The value of k is 5.

Putting k=5 in (i), we get

`w=5xy`

To find the value of w when x=4 and y=2​. Put x=4 and y=2.

`w=5(4)(2)`

`w=40`

Therefore, the value of w is 40 when x=4 and y=2​.