P, Q and R can do a certain work in 6, 7 and 14 hours respectively. They together start the work at 10.00 am . P leaves after 2 hours and Q leaves 20 minutes before the completion of the work. At what time is the work completed?

1:20 pm

p's efficiency - 16.66% work/hr
q's- 14.28%
r's- 7.14%

p+q+r for 2 hrs = (16.66+14.28+7.14)*2= 76.16% in 2 HOURS
q left 20 min before therefore r worked for last 20mins - 7.14*20/60+=2.38% in 20 MINS
remaining work was done by all three i.e- 100 - 76.16 - 2.38= 21.46% of work done in 1HOUR, ADD THESE TIME TOGETHER- 3HR 20 MINS//

34/9 hours

3 hr 20 min

3.1