# Hairu and the numbers part 17 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings on Solving Singapore Primary School Mathematics. The blog presenting the Math Concept, Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids can learn the skills of dealing with Math Question Solving, Math Modeling and Problem Sums from Lower Primary School to Upper Primary School level after reading the blog postings. This posting is an upper primary school math question on Average Number.

To read the posting on Hairu and the numbers to understand the concept of number.

You can read the posting on Sarin learns Average Number, Percentage and Charting in school (Math Concept) to understand the concept of Percentageand Charts.

Read also the posting on Sarin learns concept of Fraction in school to understand the concept of Fraction.

Challenge yourself with the question before look for the given solution‼!

Upper primary school mathematics question UPQ317

The average of 3 numbers is 72. The sum of two of the numbers is 1/6 of the sum of all the three numbers. What is the third number?

Solution:

The sum of two number is 1/6 fraction of the sum of all the three numbers.

The third number is 5/6 fraction of the sum of the three numbers.

The average number of the 3 numbers is 72.

The sum of the 3 numbers = 72 × 3 = 216

From the model,

The sum of the 3 numbers = 72 × 3 = 216

6 units = 216

1 unit = 36

The third number = 5 × 36 = 180