Question

If i am driving 45 miles per from my house to my job. My job is 35 minutes from my house. It is 9:30 i have to be there by 10:00 on the dot so how much should i increase the speed?

Answer 1

Usual speed is given by :

$s = \dfrac{45\times 60}{35} \ mph\\\\s=77.14 \ mph$

Now, we want to reach job exactly at 10 : 00 .

So, time taken is , t = 10:00 - 09:30

t = 30 minutes = 0.5 hours .

New speed is :

$s'= \dfrac{45}{0.5} = 90 \ mph$

Therefore, increase in speed is ( 90 - 77.14 ) = 12.86 mph.

Hence, this is the required solution.