Answer: 6 hours, 40 minutes
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Work Shown:
(x hours strength)/(4 hours endurance) = 5/3
x/4 = 5/3
3x = 4*5
3x = 20
x = 20/3
x = (18+2)/3
x = 18/3 + 2/3
x = 6 + 2/3
x = 6 & 2/3
He needs to spend 6 full hours, plus an additional 2/3 of an hour, on strength training.
1 hr = 60 min
2/3 hr = (2/3)*60 min
2/3 hr = 40 min
6 hr + 2/3 hr = 6 hr + 40 min
Therefore, he needs to spend 6 hours, 40 minutes on strength training.
This is equivalent to 6*60+40 = 360+40 = 400 minutes.