# Sarin participates in school anniversary event part 10 (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. You or your kids can learn dealing with Math modeling, Problem Sum from Lower Primary School to Upper Primary School level in Singapore school. This posting is a primary school math question on Fraction, Math Modeling and Problem Solving.

Read the posting on Sarin participates in school anniversary event part 1 for story on school anniversary.

To read also the posting on Sarin learns the concept of Fraction (mathematics concept) to understand the concept of Fraction.

Upper primary school mathematics question UPQ173

There were a total of 930 guests in the school anniversary dinner. After 4/5 of the male guests and ¾ of the female guests left, there were 120 more female guests than male guests that remained. How many male guests were at the school anniversary dinner at first?

Solution:

The fraction of male guests remained = 1 – 4/5 = 1/5 of all male guests

The fraction of female guests remained = 1 – 3/4 = 1/4 of all female guests

The female guests were more than male guests by 120 at the end

One unit of female guests (F) = One unit of male guests (M) + 120

1F = 1M + 120

With total number of guests at first were 930

5M + 4F = 930

5M + 4M + 4 × 120 = 930

9M = 930 – 480 = 450

1M = 50

The number of male guests at first = 5 × 50 = 250

Alternative solution:

Draw the model based on Fraction and remove guests that left

9 units = 930 – 120 × 4 = 450

1 unit = 50

The number of male guests = 5 × 50 = 250