A task is assigned to a group of 11 men, not all of whom have the same capacity to work. Every day exactly 2 men out of the group work on the task, with no pair of men working together twice. Even after all the possible pairs have worked once, all the men together had to work for exactly one day more to finish the task. What is the number of days that will be required for all the men working together to finish the job?(a) 11 (b) 21 (c) 33 (d) none of the foregoing
Suppose the work done by each man = a(i) .. where i = 1,2,3,4...11
So, the statement says that ( a1 + a2) + ( a1 + a3) + ... 55 pairs + ( a1 + a2 + a3 + a4 + .....a11) = W (work total)
On the LHS side, a1 will occur 11 times, a2, will occur 11 times and so on
=> 11*( a1 + a2 + ....a11) = W
=> If they work together, it will take 11 days .. Option a.?
Each person works for 10 days with someone else + 1 day more = 11 days.Let a(i) be the capacity(days in which work is completed) of each worker => (1/a(1) + 1/a(2) + ... + 1/a(11)) of the work in a single day = w=> 11w = 1 => All working together take 11 days to finish the work Hence, choice (a) is the right answer mjhe bhi nhi smjh aaya
tuliram runs in a triathlon consisting of 3 phases in the following manner.running 12 km,cycling 24 kkm and swimming 5 km.his speeds in the 3 phases are in the ratio 2:6:1.he completes the race in n minutes.later he changes his stratgey so that the distances he covers in each phase are constant but his speeds are now in the ratio 3:8:1.the end result is that he completes the race taking 20 mins more than the earlier speed.it is also known that he has not changed his running speed when he changes his strategy.1)what is his intial speed? ans:0.5km/min
