A few days ago
Drew T

Math Help I can’t get it to work out?

There are 2 cars, one is moving at 8.9 Km/s the other is moving at 5.1 Km/s in the same direction. When they reach a point, X Km from the starting point, they are 73 seconds apart. Solve for X

I know that

Time = Distance/Speed

And the difference in time = 73 seconds

So Time = (Distance/Speed1) – (Distance/Speed2)

So 73 = (x/8.9) – (x/5.1)

After i work it all out i get 871.965…Km but when i check my work it doesn’t come out the same, what did i do wrong?

Top 4 Answers
A few days ago
lani c

Favorite Answer

Your 871.965km is correct. Divide this distance to the respective speeds of both cars, you will get the time in seconds for both. Get the difference between these times you will get about 73 sec.

So Car A = 871/8.9 = 97.86sec

Car B = 871/5.1 = 170.78 sec

Hence their distance is 170.78-97.86 = 72.92 about 73 sec depending on how the numbers are rounded off.

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A few days ago
zi_xin
First of all, your assumption is wrong. X can’t be the same for the two cars because they are traveling at different speeds. You problem even stated that they are 73 seconds apart so there is no way they will are at the same point in space. You need to specify which X you want, the car that is going 5.1km/s or the car going 5.1km/s.

Second of all, this problem makes no sense and is unsolvable. 73 seconds is a time unit, not a distance unit. They are 73 seconds apart according to what speed, car 1 or car 2? This problem needs more info.

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A few days ago
Grandmaster_D
You are going for distance, not time, so the first figure out how far the second car moves in 73 seconds,

5.1×73=372.3 km

now, you can figure the distances as follows

8.9x=5.1x+372.3

3.8x=372.3

x=97.97 km, rounded off

see if it is true

8.9x=5.1x+372.3

8.9(97.97)=5.1(97.97)+372.3

871.9=499.6+372.3

871.9km=871.9km

You had it right, just round off, or keep all decimals, as needed or you feel best.

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A few days ago
dans95945
It works out for me when using your result.

73=871.965/8.9 – 871.965/5.1

73=97.97359 – 170.97353

73=-72.99994

If you want an answer with a positive number just put the factor with the lower denominator first.

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