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

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

Answer 2

Answer:

D. 21/2

Step-by-step 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

$\implies x = \frac{7}{2}$

Again from equation (1),

$y=\frac{7x}{2}$

For x = 3,

$y=\frac{7\times 3}{2}=\frac{21}{2}$

Hence, Option D is correct.