A Drink of Water
Weekly Problem 43 - 2015
Rachel and Ross share a bottle of water. Can you work out how much water Rachel drinks?
Rachel and Ross share a bottle of water. Can you work out how much water Rachel drinks?
Age
14 to 16
Challenge level
Problem
A bottle contains $750\text{ml}$ of mineral water. Rachel drinks $50$% more than Ross, and the two friends finish the bottle between them. How much does Rachel drink?
If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.
Student Solutions
Answer: Ross drinks 300 ml and Rachel drinks 450 ml
Using ratio
If Rachel drinks 50% more than Ross, the amount they drink is in the ratio 3 : 2
750 $\div$ 5 = 150
Rachel: 150 ml $\times$ 3 = 450 ml
Ross: 150 ml $\times$ 2 = 300 ml
Using percentage
Ross 100%
Rachel 150%
Total 250% = 750 ml
25% = 75 ml
100% = 300 ml Ross
150% = 450 ml Rachel