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Let the work ‘M’ = 24 units (LCM of 12 and 8) Efficiency of P = 24/12 = 2 units Efficiency of Q = 24/8 = 3 units Efficiency of P, Q and R = (24 × 10)/12 = 20 units per day Efficiency of R = 20 – (2 + 3) = 15 units per day Time taken by R to finish work ‘N’ = 240/15 = 16 days
A letter is taken out at random from ‘ROORKEE’ and another is taken out from ‘BOOKKEEPER’. The probability that they are the same letter is
A bag contains 14 black and 16 white balls. One ball is drawn at random. What is the probability that the ball drawn is white?
...There are 'x' one-rupee coins, 'x + 5' two-rupee coins, and 'x - 5' five-rupee coins in a purse. Two coins are drawn from the purse without replacement,...
In a factory which manufactures calculators, machines A, B and C manufacture respectively 25%, 35% and 40% of the calculators. Of their outputs, 5, 4 an...
A box contains 12 yellow marbles, ‘x’ blue marbles and 12 white marbles. A box contains 5 yellow marbles, 2 blue marbles and 3 white marbles. The ...
There are is chest containing only diamond and emeralds in the ratio 2:5. When 2 of them are picked at random form the chest, the probability that both ...
A bag contains 5 red balls, 4 green balls, and 3 yellow balls. Two balls are drawn randomly. What is the probability that both are of the same color?
A biased six-faced dice when thrown, is thrice as likely to show an odd number than an even number. If it is thrown twice, then the probability that the...
A box contains 6 blue shirts, 7 yellow shirts and 9 pink shirts. In how many ways can 4 shirts be drawn from the box, if at least one blue shirt, one ye...