Question
Motor boat covers a certain distance downstream in a
river in 20 hours. It covers the same distance upstream in 30 hours. If the speed of the water is 12 km/hr, then the speed of the boat in still water is:Solution
Let the distance be ‘D’ km According to the question, Downstream speed x + y = d/20 or d = 20 (x+y) .......... (i) Upstream speed x-y = d/30 or d = 30(x-y) ........... (ii) Comparing (i) & (ii) 20(x+y) = 30(x-y) 2(x+y) = 3(x-y) 2x + 2y = 3x - 3y x = 5y Hence, y = Speed of the current = 12 km/hour. Speed of boat, x = 5 × 12 = 60 km/hr
More Boats and streams Questions
7, 78, 324, 900,1855, 3128
191 341 221 331 251 281
Find the wrong number in the given number series.
134, 163, 194, 231, 274, 315
53, 57, 66, 82, 117, 143, 192
 44, 57, 81, 119, 170, 234, 311.
192Â Â Â 576Â Â Â 72Â Â Â 216Â Â Â 28Â Â Â 81
0 7 26 63 126 215
...71 81 61 101 51 181
Find the wrong number in given number series.
2669, 2838, 2993, 3185, 3397, 3629
119, 145, 186, 249, 340, 483
Relevant for Exams:
