document.write( "Question 422834: You take the bus to school 5 days per week. The waiting time for the next bus to arrive at your bus stop is normally distributed with a mean of 20 minutes and standard deviation of 5 minutes. Assume that the waiting times are independent from day to day. What is the probability that you wait more than 15 minutes for your bus to arrive on 3 of the 5 days next week? \n" ); document.write( "

Algebra.Com's Answer #295067 by stanbon(75887) $\"\"$ $\"About$

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You take the bus to school 5 days per week. The waiting time for the next bus to arrive at your bus stop is normally distributed with a mean of 20 minutes and standard deviation of 5 minutes. Assume that the waiting times are independent from day to day. What is the probability that you wait more than 15 minutes for your bus to arrive on 3 of the 5 days next week?
\n" ); document.write( "--------
\n" ); document.write( "Find probability of >= 15 minute wait:
\n" ); document.write( "z(15) = (15-20)/5 = -1
\n" ); document.write( "P(x > 15) = P(z > -1) = 0.8413
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\n" ); document.write( "Find probability of 3 in 5.
\n" ); document.write( "Binomial Problem with n = 5 and p = 0.8413
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\n" ); document.write( "P(x = 3) = 5C3(0.8413)^3(0.1587)^2 = 0.1500
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "

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