Question
Speed of boat in downstream is 45% more than speed of
boat in still water. If speed of stream is 9 km/h, then find the time taken by the boat to cover 81 km in downstream and 54 km in upstream.Solution
Let speed of boat in still water be ‘c’ km/h. Therefore, downstream speed of the boat = 1.45c km/h. Speed of stream = 1.45c - c = 0.45c km/h. So, 0.45c = 9. Or, c = 20. So, speed of boat in still water = 20 km/h. Upstream speed of boat = 20 - 9 = 11 km/h. Downstream speed = 20 + 9 = 29 km/h. Desired time = (81/29) + (54/11) = 2.79 + 4.91 = 7.7 hours.
More Boats and streams Questions
3,   2,   3,  8,  31,  ?
56. 23Â Â Â Â Â 45Â Â Â Â Â 89Â Â Â Â Â 177Â Â Â Â Â 363Â Â Â Â Â 705
...22Â Â Â Â Â Â Â Â Â Â 62Â Â Â Â Â Â Â Â Â Â 178Â Â Â Â Â Â Â Â 522Â Â Â Â Â Â Â Â 1550Â Â Â Â Â Â ?
...77 ? 190 257 331 412
...2, 12, 90, 240, ?, 1260
41 48 89 137 226 ?
...43 36 50 29 ? 22
...5 14 56 220 1125 6786
...7 29 ? 129 211 349
19 8 ? -14 63 - 36
...
Relevant for Exams:
