Writing equations

[susumandrai]

I just cant answer this question. Please help:

Harry finishes a 22km run-swim-bike race in 100 mins. Bike ride is twice as long as the run, and three times as long as the swim. He can bike bike three times faster than he can run. He can swim at half the speed he can run. How fast can he run?

Please write equations to solve.

 

[Deleted member 4993]

I just cant answer this question. Please help:

Harry finishes a 22km run-swim-bike race in 100 mins. Bike ride is twice as long as the run, and three times as long as the swim. He can bike bike three times faster than he can run. He can swim at half the speed he can run. How fast can he run?

Please write equations to solve.

First define your variables. Let

Length of run = R

Length of bike ride = B = 2R

Length of swim = S = 1/3 * B = 2/3 * R

Then

R + 2R + 2/3 * R = 22..................................................(1)

That is your first equation - and continue......

 

[susumandrai]

First define your variables. Let

Length of run = R

Length of bike ride = B = 2R

Length of swim = S = 1/3 * B = 2/3 * R

Then

R + 2R + 2/3 * R = 22..................................................(1)

That is your first equation - and continue......

So you have told me how to find the distances. But the second part of the question says find the speed. How would I do that?

 

[susumandrai]

So you have told me how to find the distances. But the second part of the question says find the speed. How would I do that?

Is the final answer 3.49 km/h

Please reply...

 

[pappus]

Is the final answer 3.49 km/h <--- No

Please reply...

1. You know now how to determine the distances, that means the distance he ran, the distance he biked and the distance he swam. Do so!

2. Now use the definition of speed:

\(\displaystyle speed = \frac{distance}{time}~\implies~time = \frac{distance}{speed}\)

3. You know the different speeds in relation to his running speed and you know the totally elapsed time. With these values you are able to determine the "running speed".

 

[susumandrai]

1. You know now how to determine the distances, that means the distance he ran, the distance he biked and the distance he swam. Do so!

2. Now use the definition of speed:

\(\displaystyle speed = \frac{distance}{time}~\implies~time = \frac{distance}{speed}\)

3. You know the different speeds in relation to his running speed and you know the totally elapsed time. With these values you are able to determine the "running speed".

got it....thanks everyone