Q. A alone completes the work in 24 days and B alone completes the work in 36 days and the efficiency of C is 75% of the efficiency of A. If A, B and C started the work alternatively, Starts with A, then B and then C and so on, then in how many days the work will be completed?
a) 12(7/9) days
b) 9(7/9) days
c) 10(7/9) days
d) 29(7/9) days
e) None of these
Sol:
A = 1/24
B = 1/36
C = 24 * 100/75 = 32
LCM of 24, 36 and 32 = 288
A alone completes the work in a day = 288/24 =
12 units
B alone completes the work in a day = 288/36 =
8 units
C alone completes the work in a day = 288/32 =
9 units
First three days (12 + 8 + 9) units of work are
completed.
After 9 days = 29 * 9 = 261 units completed
29th day = 261 + 20 = 281 units completed
Required time = 29 (7/9) days
