Question

Please fill in the blanks.

1)If normal distribution A has a mean of 40 and a standard deviation of 20 and normal distribution B has a mean of 40 and a standard deviation of 10, then curve is ________ and _________ than curve B. If normal distribution C had mean of 30 and a standard deviation of 20, then curve C has the same shape as curve ________ but has a different shape.

2) When np ≥ _____ and n(1-p) ≥ _______, then the normal distribution provides a reasonable approximation to the binomial distribution. If the number of trials is 100 and the probability of failure is 0.80, then the mean of the normal approximation is _______ and the standard deviation is _________.

3) The two z- scores bounding the middle 95% of a normal distribution are ________. The two z-scores bounding the middle 90% of a normal distribution are _______ and _______.

Answer 1

1)

If normal distribution A has a mean of 40 and a standard deviation of 20 and normal distribution B has a mean of 40 and a standard deviation of 10, then curve is shorter and wider than curve B. If normal distribution C had mean of 30 and a standard deviation of 20, then curve C has the same shape as curve A but has a different shape.

2)

When np ≥ 10 and n(1-p) ≥ 10 then the normal distribution provides a reasonable approximation to the binomial distribution. If the number of trials is 100 and the probability of failure is 0.80, then the meanof the normal approximation is 80(n=np) and the standard deviation is 16.

3) The two z- scores bounding the middle 95% of a normal distribution are +/-1.96. The two z-scores bounding the middle 90% of a normal distribution are 1.645 and -1.645.