 Aptitude_Q&A_01
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Useful Facts:
I) Speed (kmph), is distance (km) travelled in unit time (hr)..

II) For 2 trips of equal distances,
Speeds and Times are in opposite (inverse) ratios.

 11. Ram cycles 600m in 5 minutes. What is his speed in kmph? Solution: 12 x 5 = 60 min. Distance is 12 x 600m = 7200 m = 7.2 km. So speed is 7.2 kmph. Better: (Avoiding multiplication by 12) In 5 min., 600m; in 10 min., 1200m; in 60 min. 7200m. So speed is 7.2 kmph.

12. An aeroplane flies a certain distance at 240 kmph in 5 hrs.
At what speed the plane should fly to cover the same distance in
 1 hours?

Solution:
Ratio of time is 3 : 1
Distance is same.
So, ratio of speed is the opposite of ratio of time and so is 1 : 3.
So speed is 240 x 3 = 720 kmph.

 13. If a person walks at 14 km/h instead of 10 km/h, he would have walked 20 km more. What is the actual distance travelled by him? Solution: 4km more every hour; 20km in 5 hrs; so he walked for 5 hours. Actual distance walked is 10 x 5 = 50 km.

 14. A train can travel 50% faster than a car. Both start from point A at the same time and reach point B, 75 kms away from A at the same time. On the way, however, the train lost about 12.5 minutes while stopping at the stations. What is the speed of the car? Solution: Distance is same; 75kms. Speed ratio is Car : Train = 2 : 3. So time ratio is Car : Train = 3 : 2. The difference 1 part is 12.5 minutes. So car's time is 3 parts, which is 37.5 min. In 37.5 min, Car travels 75 kms; In 60 min, Car travels 120 kms. (Note 75 is double 37.5!) So Car's speed is 120 kmph. (Double of 60!)

 15. Excluding stoppages, the speed of a bus is 54 kmph and including stoppages, it is 45 kmph. For how many minutes does the bus stop per hour? Solution: Bus normally travels 54km in 1 hour. With stoppages, it travels only 45km in 1 hour. It stops for the equivalent time for 9km by normal speed. This is one-sixth of 1 hour (time for 54km) = 10 min. Or: Speed ratio = 54 : 45 = 6 : 5. A sixth of speed implies a sixth of the distance is lost. i.e. a sixth of the time (60 min) is lost So stops for a sixth of time, 1 hr, and this is 10 min.
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