Answer:
a) how many would you expect to fail to meet a minimum specification limit of 35-pounds tensile strength?
7933 parts
b) How many would have a tensile strength in excess of 48 pounds?
2739.95 parts
Explanation:
The formula for calculating a z-score is is z = (x-μ)/σ, where x is the raw score, μ is the population mean, and σ is the population standard deviation.
a) how many would you expect to fail to meet a minimum specification limit of 35-pounds tensile strength?
z = (x-μ)/σ
x = 35 μ = 40 , σ = 5
z = 35 - 40/5
= -5/-5
= -1
Determining the Probability value from Z-Table:
P(x<35) = 0.15866
Converting to percentage = 15.866%
We are asked how many will fail to meet this specification
We have 50,000 parts
Hence,
15.866% of 50,000 parts will fail to meet the specification
= 15.866% of 50,000
= 7933 parts
Therefore, 7933 parts will fail to meet the specifications.
b) How many would have a tensile strength in excess of 48 pounds?
z = (x-μ)/σ
x = 48 μ = 40 , σ = 5
z = 48 - 40/5
z = 8/5
z = 1.6
P-value from Z-Table:
P(x<48) = 0.9452
P(x>48) = 1 - P(x<48)
1 - 0.9452
= 0.054799
Converting to percentage
= 5.4799%
Therefore, 5.4799% will have an excess of (or will be greater than) 48 pounds
We are asked, how many would have a tensile strength in excess of 48 pounds?
This would be 5.4799% of 50,000 parts
= 5.4799% × 50,000
= 2739.95
Therefore, 2739.95 parts will have a tensile strength excess of 48 pounds