Question
Ricky can go on a motor boat with a speed of 15 km/hour
in still water to a certain upstream point and come back to the starting point in a river which flows at a speed of 5km/hour. Find the average speed of motor boat for total journey?Solution
Let, the speed of boat be b km/hour and speed of current be s km/hour Average speed = 2xy/(x+y) (here, x is speed of downstream and y is speed of upstream) = (2 (b+s)(b-s))/((b+s+b-s)) = (b2-s2)/b = (225-25)/15 = `13 1/3` km/hour
3 4.5 6.75 10.125 15.1875 22.78125 ?
...22, 23, 31, 57, 122, 247
12Â Â Â Â Â Â Â Â Â Â 8Â Â Â Â Â Â Â Â Â Â Â Â Â 6Â Â Â Â Â Â Â Â Â Â Â Â Â 12Â Â Â Â Â Â Â Â Â Â 4.5Â Â Â Â Â Â Â Â Â 15
18      �...
20 9 10 ? 29 71.5
...133    183    220    ?     263     273
...63 189 315 378 567 693
...Find the value of c.
-3Â Â Â Â Â -2Â Â Â Â -12Â Â Â Â -9Â Â Â Â -100Â Â Â Â Â Â Â -375
 31    a     �...
6 6 3 6.5 12 33
...7 29 ? 129 211 349
6Â Â Â Â Â Â Â Â Â Â Â Â Â 7Â Â Â Â Â Â Â Â Â Â Â Â Â 15Â Â Â Â Â Â Â Â Â Â 46Â Â Â Â Â Â Â Â Â Â 185Â Â Â Â Â Â Â Â ?
...
