Thursday, April 17, 2008

Ai Tong School P5 SA1 2006 Math (Q43)

The cost of a kiwi fruit was ¼ that of a rock melon. Melvin spent 4/7 of his money on 12 rock melons and 4 kiwi fruits. Then he used the remaining amount of money to buy 3 more rock melons and some kiwi fruits. How many kiwi fruits did he buy in all?

Solution

Kiwi fruit ----- 1 unit
Rock melon ----- 4 units

12 rock melons + 4 kiwi fruits ----- 4/7 of money
(12 x 4 units) + (4 units) ----- 4/7 of money
48 units + 4 units ----- 4/7 of money
52 units ----- 4/7 of money

4/7 of money ----- 52 units
1/7 of money ----- 52 units divided by 4 = 13 units

The remaining amount of money he had was 3/7, therefore
3/7 of money ----- 13 units x 3 = 39 units

He used this amount of money to buy 3 rock melons and some kiwi fruits.

3 rock melons + unknown no. of kiwi fruits ----- 39 units
(3 x 4 units) + ? ----- 39 units
12 units + ? ----- 39 units
? ----- 39 units – 13 units = 27 units

1 unit ----- 1 kiwi fruit
27 units ----- 27 kiwi fruits

Total no. of kiwi fruits bought -----
4/7 of money was spent on 12 rock lemons and 4 kiwi fruits.
3/7 of money was spent on 3 rock lemons and 27 kiwi fruits.
Total no. of kiwi fruits ----- 4 + 27 = 31

Answer: He bought a total of 31 kiwi fruits.

3 comments:

Anonymous said...

Nanyang Primary School
SA2 2006 Primary 5

Question 46:
Three girls shared a sum of money. Cathy received $180 more than Betty. The total amount Betty and Cathy received was 3 times the amount Alice received. The amount Alice and Cathy received was 5 times the amount Betty received. What was the sum of money shared by the three girls?

pls enlighten. thanks

Excel Eduservice said...

My reply can be found here.

Anonymous said...

thanks a lot.