1 Answers
Option 1 : 9.45 days
Calculation:
P's 1 day's work = 1/20
Q's 1 day's work = 1/30
R's 1 day's work = 1/10
(P + Q + R)'s 1 days work = 1/20 + 1/30 + 1/10 = 11/60
(P + Q + R)'s 6 days work = 2 × 11/60 = 11/30
Remaining work after 6 days = 1 - 11/30 = 19/30
Remaining work completed in = 19/30 × 60/11 = 38/11 days
∴ Required time to complete work = 38/11 + 6 = 104/11 ≈ 9.45 days
Alternate Method
Percentage of unit work done in 1 day by P = 100/20 = 5 units per day
Similarly,
Q = 100/30 = 10/3 = units per day
R = 100/10 = 10 units per day
(P + Q + R) work units per day = 5 + 10/3 + 10 = 55/3 units per day
(P + Q + R) 6 days working units = 2 × 55/3 = 110/3 units per day
Remaining work after 6 days - 100 - 110/3 = 190/3
Remaining work completed in = 190/3 × 3/55 = 190/55
∴ Required time to complete work = 190/55 + 6 = 104/11 ≈ 9.45 days