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
20Â Â Â 60Â Â Â Â 150Â Â Â Â 300Â Â Â 450Â Â Â ?
24 47 137 ? 2679 16049
...6Â Â Â Â Â Â Â Â Â Â Â Â Â 7Â Â Â Â Â Â Â Â Â Â Â Â Â 15Â Â Â Â Â Â Â Â Â Â 46Â Â Â Â Â Â Â Â Â Â 185Â Â Â Â Â Â Â Â ?
...203, 223, 198, 218, ?, 213
5     16     ?      66     119      200
...30 29 91 446 ? 28217
11Â Â Â 46Â Â Â 109Â Â Â 208Â Â Â Â 351Â Â Â Â ?
28 34 63 ? 769 3847
...In the question, three series I, II and III are given. Find the value of x, y and z to establish the correct relation among them and choose the correct...
30, 39, 66, ? , 174, 255
