The ratio of the number of 20-cent coins to the number of 50-cent coins to the number of $1 coins in a bag is 2 : 4 : 7. Given that the total amount of money in the bag is $47, how many coins are there altogether?
Solution
47 units ----- $47 (Total amount of money in bag is $47)
1 unit ----- $47 divided by 47 = $1
Value of 20-cent coins ----- 2 units ----- $2
Value of 50-cent coins ----- 10 units ----- $10
Value of $1 coins ----- 35 units ----- $35
No. of 20-cent coins ----- $2 divided by 20 cents ----- 10 coins
No. of 50-cent coins ----- $10 divided by 50 cents ----- 20 coins
No. of $1 coins ----- $35 divided by $1 ----- 35 coins
Total number of coins in bag
10 + 20 + 35 = 65
Answer: There were 65 coins in the bag.
Tuesday, December 11, 2007
Anglo-Chinese School (Primary) P5 SA2 2006 Math Question (Q37)
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2 comments:
isn't it faster to do this:
Ratio 20 cents: 50 cents : $1
= 2 : 4 : 7
2 x 20 cents + 4 x 50 cents + 7X 100 cents = 940 cents
4700 / 940 = 5 groups
5 x (2 + 4 + 7) = 65 coins
Dear Anonymous,
My reply can be found here.
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