Question
A boat can travel 50 km upstream in 5 hours and 60 km
downstream in 4 hours. Find the speed of the boat in still water.Solution
Let the speed of the boat in still water be x km/h and the speed of the stream be y km/h. Upstream speed = (x - y) km/h, Downstream speed = (x + y) km/h. Time taken to travel upstream = 50 ÷ (x - y) = 5 hours. Time taken to travel downstream = 60 ÷ (x + y) = 4 hours. From the first equation: 50 ÷ (x - y) = 5 ⇒ (x - y) = 10 km/h. From the second equation: 60 ÷ (x + y) = 4 ⇒ (x + y) = 15 km/h. Solving the two equations: x - y = 10 x + y = 15 Adding both equations: 2x = 25 ⇒ x = 12.5 km/h. Correct Option: b) 12.5 km/h
In nine innings of cricket, the average of a batsman is 59 runs. How many runs does he need to make it in the tenth inning to get the average score of 62?
A bowler gives 15.2 runs per wicket. He gives 32 runs and takes 4 wickets in the last match after which his average becomes 14.4 runs per wicket. How ma...
The average of 5 numbers is 54. The average of the first four is 52. Find the fifth number.
- The average score of a player in 30 matches is 42. In the next five matches, he scored 80, 70, 60, 55, and 45. What is his new average?
A cricketer scored an average of 80 runs per match in the first 22 matches. In his next 8 matches, he scored runs with an average of ‘x’ runs per ma...
The average of 20 numbers is 75. The average of the first 12 numbers is 80, while the average of the last 11 numbers is 68. If the 12th number is remove...
The average of first three numbers of a set of six numbers is 60 .The average of the second, third and fourth numbers is 20 and the average of the third...
Virat Kohli's strike rate after facing 'b' balls is 120. In the subsequent 15 balls, he scores an additional 39 runs, leading to ...
There are three classes P, Q and R. The average marks of class P is 75. The average marks of class Q is 80. The average marks of class R is 85. The aver...
A and B started a business investing Rs. 1500 for ‘x’ months and Rs. 1800 for 10 months, respectively. Out of total profit of Rs. 5000, profit shar...
