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
12, 34, 64, ?, 140, 182
196, 196, 203, 229, 292, ?
80, 116, 52, ?, 8, 204
150 - 10 × ( 7 - 2)/4 × 8 = ?
...Choose the missing term.
3F, 6G, 11I, 18L,?
What will come in place of the question mark (?) in the following series?
112, 124, 138, 154, ?, 196
100 180 294 448 648 ?
15, 23, 30, 36, 41, ?
188    178    158   ?     88    38
32   48   96   ?   720   2520
Relevant for Exams:
