Question

Suppose y varies directly with x. if y=7 when x=2, find y when x=3.

A. 6/7

B. 7/6

C. 8

D. 21/2

Answer 1

D. 21/2

Explanation:

Given,

y varies directly with x

That is, y ∝ x

⇒ y = kx -------(1)

Where, k is the constant of proportionality,

Given, for x = 2, y = 7,

From equation (1),

7 = 2x

`\implies x = (7)/(2)`

Again from equation (1),

`y=(7x)/(2)`

For x = 3,

`y=(7* 3)/(2)=(21)/(2)`

Hence, Option D is correct.

Answer 2

y
`\alpha x`
y=nx
Where n is a constant of proportionality.
When y=7, x=2
Replacing
7=2n
n=7/2
y=7/2x
When x=3, then y;
y=7/2*3
y=21/2