Reverse changing fraction bases and compare fractional production rates
Free examples and worked answers. No account needed.
Practise the method.
Reverse changing fraction bases and compare fractional production rates
Reverse changing fraction bases and compare fractional production rates
Example 1
A store sells 41 of its stock, then donates 21 items. It then sells 71 of what remains. There are now 162 items left. How many items did it start with?
Show worked answer
Answer: 280
Undo the last sale by multiplying by 67, add the 21 donated items
multiply by 34.
The original stock was 280.
Example 2
Machine A completes one batch in 8 hours; B completes one in 30 hours. A works alone for 2 hours, then both work together for 2 hours. A different machine C makes the same amount in 4 hours. What fraction of a batch does C make per hour?
Show worked answer
Answer: 12017
A and B together make 82+2(81+301)=3017 batches.
Divide by 4 hours for C's hourly rate.
Example 3
A store sells 51 of its stock, then donates 35 items. It then sells 71 of what remains. There are now 66 items left. How many items did it start with?
Show worked answer
Answer: 140
Undo the last sale by multiplying by 67, add the 35 donated items
multiply by 45.
The original stock was 140.
Put it into practice.
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