Question

A varies jointly as b and c. Find when b = 7 and c = 9, if the constant is the variation is 3.

A) 189

B) 7/3

C) 21

Answer 1

189 would be correct!

Answer 2

Option A is correct

Value of A is, 189

Explanation:

Joint variation states:

A varies jointly as b and c.

⇒
`A \propto b` and
`A \propto c`

⇒
`A \propto bc`

then the equation is in the form of:

`A = k \cdot bc`

where, k is the constant of variation.

As per the statement:

A varies jointly as b and c.

⇒
`A = k \cdot bc` ....[1]

To find A .

Substitute the given values b = 7 , c = 9 and k = 3 in [1]

then;

`A = 3 \cdot 7 \cdot 9 = 21 \cdot 9 = 189`

Therefore, the value of A is, 189