Question
The ratio of the speed of boats ‘A’ and ‘B’ in
still water is 8:9, respectively. The speed of the current is 25% of the speed of boat ‘A’ in still water. If boat ‘A’ takes 8 hours to travel 640 km downstream, then find the time taken by boat ‘B’ to travel 168 km upstream and 880 km downstream. (Note: Both the boats are rowing in the same stream.)Solution
Let the speeds of boats ‘A’ and ‘B’ in still water be 8x km/hr and 9x km/hr Therefore, speed of the current = 0.25 × 8x = 2x km/hr According to the question, 8x + 2x = 640/8 Or, 10x = 80 Or, x = 8 Therefore, upstream speed of boat ‘B’ = 9x – 2x = 7x = 56 km/hr Downstream speed of boat ‘B’ = 9x + 2x = 11x = 88 km/hr Required time taken = (168/56) + (880/88) = 3 + 10 = 13 hours
- 'N' is the largest three-digit number that leaves 4 as a remainder when divided by 8, 14 and 10. Find the sum of digits of 'N'.
The sum of (p/q)+(q/r)+(r/s)+(s/t) = (239/60). The value of ‘q’ is one less than the value of ‘s’. The average of ‘p’ and ‘s’ is 4. The ...
Find the average of the cubes of the first 7 natural numbers.
The sum of any seven consecutive natural numbers is always divisible by which of the following numbers?
- ‘N’ is the largest three-digit number that leaves 2 as a remainder when divided by 11, 13 and 4. Find the sum of digits of ‘N’.
- The average of five consecutive even numbers is 20. Find the second largest number.
Find the sum of all the numbers between 100 and 800, which are divisible by 6, 8 and 10.
There are two natural numbers such that the square of the smaller number exceeds five times the larger number by 4. Additionally, the sum of these two n...
Subtracting 30 from 14 times a number gives a result which is 50 more than 9 times the number. What is the number?
a, b and c are three integers. The sum of a and b is 61. If b is divided by a then the quotient is 2 and the remainder is 7. If cn - 2 is lar...
