The average mass of Bob and his five friends is 43 kg. Bob is 3 kg heavier than the average mass of his five friends. Find the mass of Bob.
Solution
Total mass of Bob and 5 friends -----
43 kg x 6 = 258 kg
If Bob had been 3 kg less, the total mass would be -----
258 kg – 3 kg = 255 kg
Average ---- 255 kg divided by 6 = 42.5 kg
But since Bob is 3 kg heavier -----
42.5 kg + 3 kg = 45.5 kg
Answer: The mass of Bob is 45.5 kg.
Monday, April 13, 2009
Rosyth Sch 2006 PSLE Math Prelim Q42
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1 comment:
Hi Mr Song
If Bob had been 3 kg less, the total mass would be -----
258 kg – 3 kg = 255 kg
Why? Any simpler method to solve this problem?
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