Question

If C = kd

(i) what is the relation between C and d?

(ii) find k when C = 30 and d = 6 

(iii) find C, when d = 10

Answer 1

(i) Given C = kd

⇒ `"C"/"d"` = k

This is in the form `x/y` = k

As C increases d also increases

∴ It is direct proportion

(ii) When C = 30 and d = 6, k = `"C"/"d"`

= `30/6`

k = 5

(iii) When d = 6, C = 30  ...[from (ii)]

When d = 10, C = ?

`("C"_1)/("d"_1) = ("C"_2)/("d"_2)`

`30/6 = ("C"_2)/10` .......[When d = 10]

C₂ = `(30 xx 10)/6`

C₂ = 50

C = 50