Answer: 
<u>Step-by-step explanation:</u>
It should be B because if class average will increase then the cost of books will be increased. Therefore, class average will be independent variable and cost of books will be dependant.
Hope this helps you out... :)
Answer:
0.9545
Step-by-step explanation:
To calculate the probability, we need to get the standard score or z-score of each of the scores.
Mathematically;
z-score = (x-mean)/SD
mean = 89 and SD(standard deviation) = 3
for 83, the z-score = (83-89)/3 = -6/3 = -2
for 95, the z-score = (95-89)/3 = 6/3 = 2
The probability we are to calculate has the following range;
P(-2<z<2)
we use the standard score table to estimate this;
= P(z<2) - P(z<-2)
P(z<2) = 0.97725
P(z<-2) = 0.02275
Plugging these values into the equation, we have ;
P(-2<z<2) = 0.97725 - 0.02275 = 0.9545
