Anonymous
Anonymous asked in Science & MathematicsMathematics · 2 months ago

# How to Calculate the Time Taken To Run A 20m Race Using This Formula? ?

d(t) = -(10/t+0.625) + 20

I have to substitute D with this one as well but I found this one even more confusing? Relevance
• There are no units given in your formula. If the units are assumed to be metres then the formula does not make sense since 20m would have no solutions.

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• d(t) is the distance at that time

The time will be t2 - t1

d( t2) - d(t1) = 20m I'm assuming distance in meters

Looking at the formula the distance formula is unusual

The distance will only have a limit of 20 m at time = infinity

This suggests the time of the race will be infinitely long

You could start at a different distance which suggests z different time

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• Please check out if there is any error in the given formula first.

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• Are you sure this formula is correct??

Since d(t) = 20 m, according to the formula,

....................-10

..........20 = ------------- + 20 ⇒

....................t + 0.625

....................-10

..........0 = ------------- ⇒

.................t + 0.625

..........0 = -10 which is INCONSISTENT

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• let d(t) = 20m

..............10

20 = - ------------- + 20

............t + 0.625

20(t + 0.625) = - 10 + 20(t + 0.625)

20t + 12.5 = - 10 + 20t + 12.5

20t - 20t = 12.5 - 12.5 - 10

0 = - 10

Therefore there is no solution for this problem..

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• Note, 1/2+3 does not mean the same as 1/(2+3).  To type out the equation correctly on a single line you need extra brackets:

d(t) = -(10/t+0.625) + 20

should be:

d(t) = -(10/(t+0.625)) + 20

Or even neater:

d(t) = 20 – 10/(t+0.625)

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It’s a trick question.  The race can never be completed with this relationship between d and t.

If you look at the equation:

d(t) = 20 – 10/(t+0.625)

you will see the right hand side is always less than 20, because you are subtracting 10/(t+0.625) from 20.

It would take an infinite amount of time to move 20m.  When t equals infinity, 10/(t+0.625) equals zero.

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• Taking the image as the correct equation and substituting 20 for d(t), the equation has no finite solution.

20 = -10/(t+0.625) + 20

0 = -10/(t+0.625)

0 = -10

There is no finite value of t that satisfies the equation. Check your presentation of the problem for errors and resubmit.

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• The text reads d(t) = -(10/t+0.625) + 20

but the picture shows d(t) = -10/(t+0.625) + 20

Which one is correct?

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