time and distance question

[swatinath]

If a motorist had driven 1 hr longer on a certain day and at a average rate of 5 miles per hr faster, he would have covered 70 more miles than he actually did. How many more miles would he have covered than he actually did if he had driven 2 hrs longer and at an average rate of 10 miles per hr faster on that day?

answer to be posted later.

[rohan_vus]

IMO 150 is the ans

[ashish81k]

Perfect Rohan.. Its 150

[swatinath]

Yeah..answer is 150. Could you plz explain what methodology did you follow?

[Testluv]

If a motorist had driven 1 hr longer on a certain day and at a average rate of 5 miles per hr faster, he would have covered 70 more miles than he actually did. How many more miles would he have covered than he actually did if he had driven 2 hrs longer and at an average rate of 10 miles per hr faster on that day?

answer to be posted later.

The question gives us info for how many extra miles it would have travelled at a faster rate and a longer time. It wants us to compute the extra miles travelled at an even faster rate and for an even longer time.

The trick here is to ignore the distance and time for the original journey. We only care about the speed. Once we have the original speed, it will be easy to plug to compute the distance travelled for any amount of time.

Let his original speed be "s".

Travelling at a speed of s+5 for 1 hour allowed him to cover an additional 70 miles:

Distance = speed * time

70 = (s + 5) (1)

S = 65.

So his original speed was 65. If we add 10 to this, we have 75. Travelling at this speed for 2 hours, the number of additional miles covered would be:

75*2 = 150.