Well, since MAD means Mean absolute divation, you will just do that between the 2 sets... i dont want to just gie the answer to you...i want you to figure it out with help because that is the only way you will learn.
The one year-plan would have a credit, so it would have a positive sign. In the monthly plan, there is a high risk of being late in paying the bills. That's why a fine of $10 is given for every month that you are late. If you are not time conscious and you end up being late every month, it would give you a negative balance.
Answer:
Firstly you have to know the x and y points,
then you use the coordinate grid to plot the points and then draw the graph from the points that has been plotted.
Hopefully this helps :)
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

=> 