Question
A boat takes 7 hours to cover 245 km upstream and 9
hours to cover 477 km downstream. Find the time taken by the boat to cover 410 km upstream and 495 km downstream if speed of boat in still water is increased by 4 km/h and speed of stream is decreased by 2 km/h.Solution
Upstream speed = 245/7 = 35 km/h Downstream speed = 477/9 = 53 km/h Speed of boat in still water = (35 + 53)/2 = 44 km/h  Speed of stream = (53 – 35)/2 = 9 km/h Increased speed of boat in still water = 44 + 4 = 48 km/h Decreased speed of stream = 9 – 2 = 7 km/h Required time taken = 410/(48 – 7) + 495/(48 + 7) = 10 + 9 = 19 hours
9Â Â Â Â Â Â Â Â Â Â Â Â Â 17Â Â Â Â Â Â Â Â Â Â 53Â Â Â Â Â Â Â Â Â Â 103Â Â Â Â Â Â Â Â 310Â Â Â Â Â Â Â Â 619
...Find the Wrong number in the given number series.
3, 6, 2, 8, 2.4, 9.6
Find the wrong number in the given number series.
65, 91, 130, 182, 286, 429
12, 18, 40, 90, 270, 945
Find the wrong number in the given number series.
2, 3, 5, 7, 11, 13, 17, 20- Find the wrong number in the given number series.
5, 8, 18, 24, 37, 48 A-5,  A,  35,  52, 78, 115
21, 32, 45, 60, 75, 96
552, 448, 380, 306, 240, 182
Find the wrong number in the given number series.
11, 20, 38, 78, 154, 310
