Answer:
-2
Step-by-step explanation:
-10 x 12 x -4 + 40 x -2 x 6 - 2
-120 x -4 - 80 x 6 - 2
480 - 480 - 2
0 - 2
-2
122.5.
A=b x h/2. A=122.5 b=7
A x b=h
122.5 x 7 =122.5
Answer: 2.28 %
Step-by-step explanation:
Given : Mean : 
Standard deviation :
The formula to calculate the z-score :-

For x = 72

The p-value = 

In percent, 
Hence, the percentage of pediatricians work more than 72 h per week = 2.28 %
It should be 12 ft away from the wall. Not 4 ft. You do not just subtract the difference because as you pull it away from the wall, the ladder is mostly moving horizontally with only a small vertical change.
You can use Pythagorean Theorem to find the answer. Think of the ladder as the hypotenuse of a right triangle with the wall and the ground as the legs.
a^2 + b^2 = c^2
16^2 + b^2 = 20^2
b^2 = 20^2 - 16^2
b^2 = 144
b = 12 ft