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  • one year ago

Between 7:00 AM and 8:00 AM, trains arrive at a subway station at a rate of 12 trains per hour (0.2 trains per minute). The following formula from statistics can be used to determine the probability that a train will arrive within t minutes of 7:00 AM. F(t)=1-e^-0.2t. Determine how many minutes are needed for the probability to reach 60%. Trying to use formula Y=C^(k*x) Y is the output, C is initial, K is %, and x is time.

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  1. anonymous
    • one year ago
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    In case someone else gets this: 1-e^-.08t=.6 (.6 is the 60%), then minus 1 from each side, -e^-.08t=-.4 , now divide off the negatives e^-.08t=.4 , now get rid of e with it's inverse of ln to both sides -.08t=ln(.4) , the divide the -.08 to each side and use calculator t= ln(.4)/(-.08) t = approximately 11 minutes. Hopefully someone can use this formula to solve like problems.

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