Question

Which ratio is not equivalent to 15:18?
A. 60:72
B. 35:42
C. 90:105
D.25:30

Answer 1

The ratio 90: 105 is not equivalent to 15: 18 ⇒ C

Explanation:

Let us simplify the given ratio to its simplest form first

∵ The ratio is 15: 18

∵ 15 and 18 have a common factor 3

→ Divide each term of the ratio by 3

∴
`(15)/(3)` :
`(18)/(3)` = 5: 6

∴ The simplest form of ratio 15: 18 is 5: 6

Let us find which choice will not give us the same ratio 5: 6

∵ 60: 72 have a common factor 12

→ Divide each term of the ratio by 12

∵
`(60)/(12)` :
`(72)/(12)` = 5: 6

∴ The simplest form of ratio 60: 72 is 5: 6

∴ The ratio 60: 72 is equivalent to 15: 18

∵ 35: 42 have a common factor 7

→ Divide each term of the ratio by 7

∵
`(35)/(7)` :
`(42)/(7)` = 5: 6

∴ The simplest form of ratio 35: 42 is 5: 6

∴ The ratio 35: 42 is equivalent to 15: 18

∵ 90: 105 have a common factor 15

→ Divide each term of the ratio by 15

∵
`(90)/(15)` :
`(105)/(15)` = 6: 7

∴ The simplest form of ratio 90: 105 is 6: 7

∴ The ratio 90: 105 is not equivalent to 15: 18