Answer:
37 7/15 minutes
Step-by-step explanation:
The winner took 2 1/5 minutes less than the 39 2/3 minutes taken by the second place finisher. That time is ...
... 39 2/3 - 2 1/5 = (39 -2) + (2/3 -1/5) = 37 + (5·2 -3·1)/(3·5)
... = 37 7/15 . . . . minutes
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It might be easier to compute the time in minutes and seconds.
... 39 2/3 minutes = 39 minutes 40 seconds
... 2 1/5 minutes = 2 minutes 12 seconds
Then the difference is ...
... (39 -2) minutes (40 -12) seconds = 37 minutes 28 seconds
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Adding fractions
The sum of fractions a/b and c/d can be found as ...
... a/b + c/d = (ad +bc)/(bd)
For a=2, b=3, c=-1, d=5, the sum is (2·5+3·(-1))/(3·5) = (10-3)/15 = 7/15
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Time conversions
A minute is 60 seconds, so the number of seconds in a fraction of a minute is found by multiplying that fraction by 60 seconds.
... 2/3 × 60 seconds = 40 seconds
... 1/5 × 60 seconds = 12 seconds
... 7/15 × 60 seconds = 28 seconds
