I always forget formulas!!! This question has a formula:

Sarah and Jack are in a running race. Jack ran at 6 mph. Sarah ran at 4 mph. Jack finished the race 1 hour before Sarah. How long was the race?

What is the formula to that question?

Pyramid
Oct 2, 2014

#1**+18 **

We have.......

Rate*Time = Distance ...... so let Jack's time be "T' ....and we have 6T = D

And since Sarah ran 1 hour more, we have...... R(T + 1) = D → 4(T + 1) = D

And since the distances are the same, we have

6T = 4(T + 1) ....simplify

6T = 4T + 4 ...... subtract 4T from both sides

2T = 4 ....... divide by 2 on both sides

T = 2 hrs = Jack's time ... and Sarah's time was 1 hour more = 3 hrs.

So, the race was 6mph*(2hrs) = 4mph*(2 + 1)hrs = 4mph(3 hrs) = 12 miles !!!

CPhill
Oct 2, 2014

#1**+18 **

Best Answer

We have.......

Rate*Time = Distance ...... so let Jack's time be "T' ....and we have 6T = D

And since Sarah ran 1 hour more, we have...... R(T + 1) = D → 4(T + 1) = D

And since the distances are the same, we have

6T = 4(T + 1) ....simplify

6T = 4T + 4 ...... subtract 4T from both sides

2T = 4 ....... divide by 2 on both sides

T = 2 hrs = Jack's time ... and Sarah's time was 1 hour more = 3 hrs.

So, the race was 6mph*(2hrs) = 4mph*(2 + 1)hrs = 4mph(3 hrs) = 12 miles !!!

CPhill
Oct 2, 2014