Problema Solution

Last year, Leah used 10 bottles of shampoo and 8 bottles of conditioner. Her sister, Kelsey, used 7 bottles of shampoo and 5 bottles of conditioner. Who used a higher ratio of shampoo to conditioner last year?

Answer provided by our tutors

Leah's ratio of shampoo to conditioner: 10/8 = 5/4

Kelsey's ratio of shampoo to conditioner: 7/5

Since LCM(4, 5) = 20 we have: 

5/4 = (5*5)/(4*5) = 25/20

7/5 = (7*4)/(5*4) = 28/20

28/20 > 25/20 meaning 7/5 > 5/4

Kelsey used higher ratio of shampoo to conditioner last year.