Answer:
a
i So the approximate distribution of
is
and 
ii So the approximate distribution of
is
and 
b
the approximate distribution of
is
and 
Here we can see that the mean of the approximate distribution is negative which tell us that this negative value of the data for
sample are more and their frequency occurrence is higher than the positive values
c
the value of
is
Step-by-step explanation:
From the question we are given that
The expected tensile strength of the type A steel is 
The standard deviation of type A steel is 
The expected tensile strength of the type B steel is
The standard deviation of type B steel is 
Also the assumptions are
Let
be the sample average tensile strength of a random sample of 80 type-A specimens
Here 
Let
be the sample average tensile strength of a random sample of 60 type-B specimens.
Here 
Let the sampling distribution of the mean be


Let the sampling distribution of the standard deviation be



So What this mean is that the approximate distribution of
is
and 
For 
The sampling distribution of the sample mean is


The sampling distribution of the standard deviation is



So What this mean is that the approximate distribution of
is
and
Now to obtain the approximate distribution for 




The standard deviation of
is



Now to find the value of 
Let us assume that 
![= P [\frac{-1 -E (F)}{\sigma_F} \le Z \le \frac{1-E(F)}{\sigma_F} ]](https://tex.z-dn.net/?f=%3D%20P%20%5B%5Cfrac%7B-1%20-E%20%28F%29%7D%7B%5Csigma_F%7D%20%5Cle%20Z%20%5Cle%20%20%5Cfrac%7B1-E%28F%29%7D%7B%5Csigma_F%7D%20%5D)
![= P[\frac{-1-(-2)}{1.029} \le Z \le \frac{1-(-2)}{1.029} ]](https://tex.z-dn.net/?f=%3D%20P%5B%5Cfrac%7B-1-%28-2%29%7D%7B1.029%7D%20%20%5Cle%20%20Z%20%5Cle%20%20%5Cfrac%7B1-%28-2%29%7D%7B1.029%7D%20%5D)
![= P[0.972 \le Z \le 2.95]](https://tex.z-dn.net/?f=%3D%20%20P%5B0.972%20%5Cle%20Z%20%5Cle%202.95%5D)

Using the z-table to obtain their z-score

