Question

A alone can finish the work in 10 hours, b alone can finish the work in 12 hours and c alone can finish the work in 15 hours. A, b and c together started working at 11'o clock. After 2 hours a leaves. When will b & c will together will finish the work?

a.4' o clock

b. 5'0 clock

c.4:20

d. 5:20

Answer 1

Answer:

Step-by-step explanation:

a = 10                                  

b = 12                             LCM of 10,12,15 = 60

c = 15

work by a in 1 hour = 60/10 = 6

" " " " " " b in " " "" "  = 60/12 = 5

" " " "" " c " " " " " " " =  60/15 = 4

all started together

a+b+c = 15

a+b+c in 2 hour = 30 work

Left worh = 30

b+c = 9

time taken = 30/9 = 3 hour 20 min.

Total time taken = 2 hour+3hour 20min = 5 hour 20 min

time at which work finished = 4:20