Answer: 0.0775
Step-by-step explanation:
Given : Mean : 
Standard deviation : 
Sample size : 
Since its normal distribution , then the formula to calculate the z-score is given by :-
For x= 28.2 hours
For x= 30 hours
The P- value = 
Hence, the probabiliy that the average time spent stydying for the sampe was between 28.2 and 30 hours = 0.0775
18 times .031 is .558
18 dollars minus .558 cents is 17.442
Answer is he was maki 17.442 dollars before the increase
The most simple way is to get 8 questions right on a ten question test. 8q/10q = 80%.
Check the picture below.
notice the bottom part of the picture, just using the tangent of the angle, we can get the angle itself, and you'd know what "x" and "y" are from the above part.
how much farther would they have to walk up? well, the hypotenuse of the longer triangle is "h", the hypotenuse of the shorter triangle is 122, so, they'd have to walk " h - 122 " more.
