Answer:
1)13(left)
2)52(right)
3)48
4)51.923
Step-by-step explanation:
a^2+b^2=C^2
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

=> 
Answer:

Step-by-step explanation:
just means
.
So

Answer:x=7
y=2 5/6
Step-by-step explanation:
6(x-5)=12
6x-30=12
6x=12+30
6x=42
6x/6=42/6
x=7
6y-5=12
6y=12+5
6y=17
6y/6=17/6
y=2 5/6