Question
A boat moves in a river where the ratio of the speed of
the stream to the downstream speed of the boat is 1:6. If it takes the boat a total of 20 hours to travel 144 km downstream and return 144 km upstream, how much time will it take to cover 180 km in still water?Solution
ATQ,
Let the downstream speed of a boat and the speed of stream be 6x km/hr and 'x' km/hr respectively.
Or, upstream speed of boat = 6x - x - x = 4x km/hr
ATQ,
(144/6x) + (144/4x) = 20
Or, (24/x) + (36/x) = 20
Or, (60/x) = 20
So, 'x' = 3
So, speed of boat in still water = 6x - x = 5x = 5 × 3 = 15 km/hr
So, required time = (180/15) = 12 hours
- Find the wrong number in the given number series.
8, 14, 24, 49, 59, 84 Find the wrong number in the given number series.
8, 12, 23, 40, 66, 103
174 180 198 252 414 910
640 1920 240 720 92 270
Find the wrong number in the given number series.
132, 147, 138, 155, 144, 161
1 3 7 15 33
...Find the wrong number in the given number series,
9, 60, 299, 1199, 3599, 7199
- Find the wrong number in the given number series.
32.6, 36.4, 40.2, 43.6, 47.8, 51.6 11 110 978 6824 34103 102290
- Find the wrong number in the given number series.
12, 21, 5, 38, 2, 71
Relevant for Exams:
