Question

2)
a: b is 2:5 and b: c is 3:8
Work out a:c
Give your answer in its simplest form.

Answer 1

a : c = 3 : 20

Explanation:

Given ratios:

• a : b = 2 : 5
• b : c = 3 : 8

The value of b is 3 and 5.

The lowest common multiple of 3 and 5 is 15.

Multiply each ratio by a factor of 15 so that b is 15.

Multiply ratio a : b by 3:

⇒ a : b = 6 : 15

Multiply ratio b : c by 5:

⇒ b : c = 15 : 40

Therefore:

⇒ a : b : c = 6 : 15 : 40

So a : c is:

⇒ a : c = 6 : 40

Simplest form:

⇒ a : c = 3 : 20