Question 104538
bob does 1/5 of the job in 1 minute.
sarah does 1/10 otj in 1 min.
gary does 1/15 otj in 1 min.
.
1/5+1/10+1/15=6/30+3/30+2/30=11/30 otj is done by the three of the in 1 minute.
So it takes 30/11 min to complete the job or 2 8/11 min or about 2 min 44 sec.