Question
A car covers a certain distance at the speed of 30 km/h
and comes back at the speed of 20 km/h. What is the average speed of the car for the entire journey?Solution
Let the distance be x km. Time taken to go = x / 30 hours, Time taken to return = x / 20 hours. Total time taken = x / 30 + x / 20 = (2x + 3x) / 60 = 5x / 60 = x / 12 hours. Average speed = Total distance / Total time = (2x) / (x / 12) = 24 km/h.
2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 4Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 5Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 19Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 70...
6000 3002 1503 ? 378.75 191.375 97.6875
...If  204    196       223   x  284
Then, what is the average of the numbers of the above series?
...8   24    12    ?   18     54
3 ? 7 16 71 346
...104   106   110   113   ?   126
12, 18, 28, 42, 52, ?
18Â Â Â Â Â Â Â Â Â Â Â Â 29 Â Â Â Â Â Â Â Â Â Â Â Â Â Â 51 Â Â Â Â Â Â Â Â 84 Â Â Â Â Â Â Â Â 128 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 182
5, 8, 17, ?, 37, 48
(32.03 + 111.98) ÷ 18.211 = 89.9 – 20.23% of ?
