Question

The mass, m, of an object varies directly as the cube of its length, I.

Answer 1

Answer:

m = 686.

Step-by-step explanation:

Direct variation :

m= kl^3 where k is a constant.

m = 250 when l = 5, so

250 = k *(5)^3

k = 250 / 125 = 2

So the equation of variation is m = 2l^3.

When l = 7:

m = 2 * (7)*3

= 2 * 343

= 686.

Answer 2

Answer: 350

Step-by-step explanation:

m = kl (1)

Let 'k' be the constant of proportionality

When, m = 250

l = 5

inputting the values into equation (1)

250 = k5

dividing both sides by 5

250/5 = k5/5

50 = k

To find m, when l =7,

Given m = kl

where k = 50 and l = 7

m = 50 x 7

m = 350