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A physical fitness association is including the mile run in its secondary-school fitness test. The time for this event for boys in secondary school is known to possess a normal distribution with a mean of 450 seconds and a standard deviation of 50 seconds. Find the probability that a randomly selected boy in secondary school can run the mile in less than 335 seconds.

Is the answer 0.0107? Anyone please

  • Alegebra -

    can some one please help me!!!

  • Alegebra -

    You are given the normal model N(450, 50)

    Find the z score for 335 seconds.
    z = (x-u)/s
    where u = mu and s = sigma.

    z = (335-450)/50
    z = -2.3

    Now use the normal cumulative distribution function on a calculator or program to find the P(z<-2.3)

    normalCDF(-99,-2.3) = .0107

  • Alegebra -

    Marth this are my choices
    A) 0.9893
    B) 0.0107
    C) 0.4893
    D) 0.5107

    So I'm assuming it's letter B? correct

  • Alegebra -

    Dahhhh lol

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