9514 1404 393
Answer:
3 1/2 hours
Explanation:
If there are 8/7 times as many cooks, it will take 7/8 the amount of time. (That's what "inversely proportional" means.)
(7/8)(4 h) = 28/8 h = 3 1/2 h
It will take 8 cooks 3 1/2 hours to prepare the dinner.