# Sarin’s family and Ramadan Part 3 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings about 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 deal with Math Modeling, Problem Sum from Lower Primary School to Upper Primary School level. This posting is an upper primary school math question on Fraction, Speed and Problem Sum.

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 UPQ231

Sarin and his father painted the living room during Ramadan and get it ready for the coming Hari Raya festive. If Sarin and his father work together, they will need 12days to complete the painting. They both painted the living room for 3 days before Sarin painted it by himself for 5 days. In total, 5/12 of the painting work is completed. How long will needed to paint the living room if Sarin or his father is painting the living room by himself?

Solution:

Both of them work together need 12days to finish painting the living room

Their combine speed = 1/12 per room

Sarin and his father paint the hosue for 3 days

The fraction of the work completed by two of them = 3 × 1/12 = 3/12

The fraction of the work completed by Sarin = 5/12 – 3/12 = 2/12 = 1/6

The number of days needed by Sarin to paint the room himself = 5 × 6 = 30

The speed of Sarin = 1/30 per room

The speed of his father = 1/12 – 1/30 = 5/60 – 2/60 = 3/60 = 1/20 per room

The number of days needed by his father to paint the room himself = 20