Question

Complete the following table considering that the cost of apples and their number are in direct variation.

Number of apples (x)	1	4	______	12	______
Cost of apples (y)	8	32	56	______	160

Answer 1

It is given that the cost of apples (y) and number of apples (x) are in direct variation.

\[\therefore y \propto x \Rightarrow y = kx\]

where k is constant of variation

When x = 1, y = 8.

∴ 8 = k × 1

⇒ k = 8

So, the equation of variation is 

y = 8x

When y = 56,  

56 = 8x 

⇒ x = 7

When x = 12, 

y = 8 × 12 = 96

When y = 160,  

160 = 8x 

⇒ x = 20

The complete is given below.

Number of apples (x)	1	4	7	12	20
Cost of apples (y)	8	32	56	96	160