In: Statistics and Probability
For a normal population with ? = 70 and ? = 12, find the following.
(a) What is the probability of obtaining a sample mean greater than 73 for a sample of n = 36 scores?
(b) What is the probability of obtaining a sample mean greater than 73 for a sample of n = 9 scores?
What type of problem is this?
What am I solving (looking) for?
a) given ? = 70 and ? = 12
probability of obtaining a sample mean
P( x>73) = x - ? / ? / sqrt(n)
= 73-70 / 12 / sqrt(36)
= 3/ 12/ 6
= 3/2
=1.5
P( x > 1.5) = 1? P( Z<1.5 )=1?0.9332=0.0668
b)
P( x>73) = x - ? / ? / sqrt(n)
= 73-70 / 12 / sqrt(9)
= 3/ 12/ 3
= 3/4
=0.75
P( x > 0.75) = 1? P( Z< 0.75 ) = 1?0.7734 = 0.2266