In: Math
The distribution of results from a cholesterol test has a mean
of 180 and a standard deviation of 20. A sample size of 40 is drawn
randomly.
Find the probability that the sum of the 40 values is less than
6,950.
Solution :
Given that,
mean = = 180
standard deviation = = 20
n = 40
= 180
= / n = 20 40 = 3.1623
= (x / n)
= 6950 / 40
= 173.75
P( < 173.75 )
P ( - /) < ( 173.75 - 180 / 3.1623)
P ( z < -6.25 / 3.1623 )
P ( z < - 1.98 )
= 0.0239
Probability = 0.0239