Kevin takes 12h to shovel, dave 8h, john 6h, allison 4h. if they work together how many minutes will they need

To shovel all of the snow, Kevin needs 12 hours, Dave needs 8 hours, John needs 6 hours, and Allison needs 5 hours. If they work together, how many minutes do they need to shovel all of Kevin's snow?

the options are:
A-108
B-120
C-84
D-96
E-90

Thank you for your help

D) 96 min
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Each hour Kevin, Dave, John, and Allison, each can shovel 1/12, 1/8, 1/6 and 1/4 of the work, respectively.

If work together, 1/12 + 1/8 + 1/6 + 1/4 = 2/24 + 3/24 + 4/24 + 6/24 = 15/24 of the work will Accomplished under one hour

The total work = 100% = 1
1 / 15/24 = 24/15 We need 24/15 hours = 1 9/15 hours = 1 36/60 hours (changed hr ==> min)

We need 60 + 36 min = 96min

The correct answer is D), 96min

Convert all to shoveling/min.
kevin = 1/12 * 60 = 5
dave = 1/8 * 60 = 15/2
john = 1/6 * 60 = 10
allison = 1/4 * 60 = 15


Add them all together.
5 + 15/2 + 10 + 15 = 37.5 minutes