I believe the answer is 3
Answer:

Step-by-step explanation:
I have attached the explanation above. hopefully this will help
Answer:
a
Step-by-step explanation:
theres a 90 degree angle and a has a 95 so thats pretty close
1. C
2. A
3. D
4. 62/25
5. 4/33
By the way it is not fair. posting 5 sums for just 7 points. :)
anyway, if it helped u
do click thx.
Answer:
a

b

Step-by-step explanation:
From the question we are told that
The mean value is 
The standard deviation is 
Considering question a
The sample size is n = 9
Generally the standard error of the mean is mathematically represented as

=>
=> 
Generally the probability that the sample mean hardness for a random sample of 9 pins is at least 51 is mathematically represented as



=> 
From the z table the area under the normal curve to the left corresponding to 2.5 is

=> 
=> 
Considering question b
The sample size is n = 40
Generally the standard error of the mean is mathematically represented as

=>
=> 
Generally the (approximate) probability that the sample mean hardness for a random sample of 40 pins is at least 51 is mathematically represented as

=> 
=> 
From the z table the area under the normal curve to the left corresponding to 5.2715 and
=> 
So

=> 