In: Statistics and Probability
The average tensile strength for a particular aircraft bolt is 32.06 kN with a variance of 0.01 kN. What proportion of bolts will have a tensile strength less than 31.9 and more than 32.3 kN?
This was all the information given.
If not possible to solve please state why.
Define random variable X be the tensile strength for a particular aircraft bolt.
Assume that the X has normal distribution with mean and standard deviation are,
Average tensile strength for particular aircraft bolt =
Variance =
Standard deviation =
Here we have to find P(31.9 < X < 32.3)
= P(-1.6 < z < 2.4) where z is standard normal variable
= P(z < 2.4) - P(z < -1.6)
= 0.9918 - 0.0548 (From statistical table of z values)
= 0.937
Proportion of bolts having a tensile strength less than 31.9 and more than 32.3 kN is 0.937