Answer:
Population Mean = 2.0
Population Standard deviation = 0.03
Step-by-step explanation:
We are given that the inspector selects simple random samples of 30 finished products and computes the sample mean product weight.
Also, test results over a long period of time show that 5% of the values are over 2.1 pounds and 5% are under 1.9 pounds.
Now, mean of the population is given the average of two extreme boundaries because mean lies exactly in the middle of the distribution.
So, Mean, =
= 2.0
Therefore, mean for the population of products produced with this process is 2.
Since, we are given that 5% of the values are under 1.9 pounds so we will calculate the z score value corresponding to a probability of 5% i.e.
z = -1.6449 {from z % table}
We know that z formula is given by ;
~ N(0,1)
-1.6449 = ⇒
⇒ 0.0608 *
{as sample size is given 30}
⇒ = 0.03 .
Therefore, Standard deviation for the population of products produced with this process is 0.0333.