Question 1133711
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A solution by a very different method....<br>
Admittedly, not many people will solve the problem this way; but it works for me.<br>
When Kevin's sister helps him, stuffing 1300 shrimp takes 3/4 as long.
That means together they work 4/3 as fast as Kevin alone.
That means his sister works 1/3 as fast as Kevin.
So his sister alone would take 4*3=12 hours to stuff 1300 shrimp.
And so it would take her 6 hours to stuff 650 shrimp (half of 1300).