Complete Question
The complete question is shown on the first uploaded image
Answer:
The calcium level that is the borderline between low calcium levels and those not considered low is 
Step-by-step explanation:
From the question we are told that
The mean is 
The standard deviation 
The proportion of the population with low calcium level is
5% = 0.05
Let X be a X random calcium level
Now the P(X < c) = 0.05
Here P denotes probability
c is population with calcium level at the borderline
Since the calcium level is normally distributed the z-value is evaluated as

The critical value for 0.05 from the standard normal distribution table is

=> 
substituting values

=> 
=> 
I think it’s D. 156 degrees
Remember that the area of a square is just one of its sides squared.

where

is the area of the square

is one of the sides of the square
Unit square is a square whose sides have length 1, so lets use our formula to find the volume of one unit square:



We now know that each one of the squares has area 1 unit squared. Since there are 28 unit square in our figure, we are going to multiply the area of a unit square by 28 to find the area of our figure:
Area of the figure=

units squared
We can conclude that the area of the figure is 28 units squared.
36:12. 36 is the teeth on the front socket and 12 is the teeth on the rear socket.
All you need to do is simplify by finding the greatest common factor (GCF) of 36 and 12-which is 12, then divide by the GCF. This gives you 3:1. The gear ratio for the bike is 3 teeth on the front socket for every 1 teeth on the rear socket (3:1)