# Sarin’s family celebrating Hari Raya Puasa part 13 (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 acquire the skills to deal with Math Modeling, Math Problem Solving and Problem Sum from Lower Primary School to Upper Primary School level after reading the blog postings. This posting is an upper primary school math question on FractionRatio and Problem Sum.

You can read the postings on Sarin’s family celebrating Hari Raya Puasa and Sarin’s family and Ramadan in Welcome page about story of Sarin’s family during Ramadan and Hari Raya Puasa.

To read also the postings on Sarin learns the concept of Fraction (mathematics concept) and  Sarin learns concept of ratio in school to understand the concept of Ratio.

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

Upper primary school mathematics question UPQ303

Sarin’s mother prepared three types of Malay Kuehs for the guests during their Hari Raya Puasa openhouse event. She prepared 24 more Ondeh-ondeh than Putu Pining. She also prepared 48 more Putu Pining than Kueh Lapis. Their guests love the kuehs and ate 2/3 of the Ondeh-ondeh, 3/4 of the Putu Pining and 1/2 of the Kueh Lapis. There were altogether 101 kuehs left at the end of the day. How many Ondeh-ondeh did Sarin’s mother prepare?

Solution:

Start the model use Kueh Lapis as the base line

Normalising Kueh Lapis to 12 Units for easy computation

You can draw the model as shown

The model shown the total kuehs Sarin’s mother prepared

The guests ate 2/3 of the Ondeh-ondeh, 3/4 of the Putu Pining and 1/2 of the Kueh Lapis.

Re-make a model based the number of kuehs left

From the model

13 units = 101 – 12 – 16 – 8 = 65

1 unit = 5

The number of Ondeh-ondeh prepared by Sarin’s mother = 4 × 12 + 48 + 24 = 132

Alternative solution:

Set the number of Kueh Lapis as 1U

The ratio of Kuehs prepared by Sarin’s mother

Kueh Lapis (K) : Putu Pining (P) : Ondeh-ondeh (O) = 1U : (1U + 48) : (1U + 48 + 24)

K : P : O = 1U : (1U + 48) : (1U + 72)

The guests ate 2/3 of the Ondeh-ondeh, 3/4 of the Putu Pining and 1/2 of the Kueh Lapis.

The kuehs left in fraction are 1/3 of the ondeh-ondeh, ¼ of the Putu Pining and ½ of the Kueh Lapis

The ratio of kuehs left

K : P : O = ½ U : ¼ (1U + 48) : 1/3 (1U + 72)

K : P : O = 6U/12 : 3 (1U + 48)/12 : 4 (1U + 72)/12

K : P : O = 6U/12 : (3U + 144)/12 : (4U + 288)/12

The number of kuehs left is = 101

6U + 3U + 144 + 4U + 288 = 101 × 12

13U = 780

1U = 60

The number of Ondeh-ondeh prepared by Sarin’s mother =  60 + 72 = 132