Math
posted by Chris .
A physical fitness association is including the mile run in its secondaryschool 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.

The mean is 450 seconds and the standard deviation is 50 seconds.
Number of standard deviations below mean
=(450335)/50 = 2.3
Since it is assumed to be normally distributed, look up the normal distribution table to get the probability of 2.3 standard deviations lower than the mean. (approx. 1%) 
) A physical fitness association is including the mile run in its secondaryschool 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 60 seconds. Find the probability that a randomly
selected boy in secondary school can run the mile in less than 312 seconds.