Question
Tap ‘A’ and tap ‘B’ can fill a tank in 42 hours
and 30 hours, respectively. If both taps are opened together, then find the time after which tap ‘A’ must be closed so the whole tank can be filled in 20 hours.Solution
Let total capacity of the tank is 210 litres (LCM of 42 and 30) Quantity of water filled by tap ‘A’ in one hour = 210/42 = 5 litres Quantity of water filled by tap ‘B’ in one hour = 210/30 = 7 litres Let tap ‘A’ is closed after ‘x’ hours So, 12 × x + 7 × (20 – x) = 210 Or, 5x = 70 Or, x = 14 hours
16 rotten bananas are accidentally mixed with 155 good ones. It is not possible to just look at a banana and tell whether or not it is rotten. One banan...
10 rotten bananas are accidentally mixed with 140 good ones. It is not possible to just look at a banana and tell whether or not it is rotten. One banan...
What will be the probability of choosing one red and one green ball from a basket containing 4 red and 5 green balls if two balls are drawn randomly?
Three houses are available in a locality. Three persons apply for the houses. Each applies for one house without consulting others. The probabili...
John is answering a survey with 3 questions, each with 2 options. Only one option is correct per question. If John answers randomly, what is the probabi...
What is the probability that a number selected from 1,2,3.......................68,69,70, is perfect square or a perfect cube?
A box contains 8 yellow marbles, ‘x’ blue marbles and 12 white marbles. A box contains 5 yellow marbles, 2 blue marbles and 3 white marbles. The pro...
A box contains 5 red, 6 green and 3 yellow balls. 2 balls are drawn at random. What is the probability that they are not of the same colour?
The probability of selecting a rotten egg randomly from a basket of 250 eggs is 0.2. What is the number of rotten eggs in the basket?
A bag contains 13 white and some black balls. If the probability of drawing a black ball from the bag is 3 times that of drawing a white ball, find the ...
Relevant for Exams:
