Question

10. Sohan misses his school bus and asks his father for a lin in his car
. If his school is 8 km away
and he has to reach there in exactly fifteen minutes, at what speed (in km/hr) should his father
drive? Being on time is a good thing. Why? (Value Corner)​

Answer 1

Answer:

15 minutes is 1 quarter of an hour , and therefore 4 x 15 minute quarters makes up 1 hour . So travelling at 8 km/hr RAM would get there in one hour but to get there in 15 minutes multiply the 8 km by 4 (quarters) you have to travel 4 times faster to get there in One forth of the time, so 8x4 = 32 km/hr is the average speed you need to drive . Given that it is almost impossible to drive at a constant speed for the 8 km it may mean that you need to drive at a higher top speed especially if you have to stop . So say that you had to slow down and stop for 1 minute. This means to still get there in 15 minutes you need to drive one of the other minutes at 64 km/hr to maintain the 32 km/hr average . This supposes that your slow down deceleration speed of going from 32 to 0 is equivalent to the acceleration speed going from 0 to 64 and deceleration back to 32 km/hr. Or alternatively driv for two minutes at 48 km/hr if 64km/hr is over the speed limit…

So why should you not be late. It’s so that you learn this sort of math in school. And don’t get us to do it while giving you ribbing for not knowing this sort of thing already