Factorize using the difference of squares identity.

Then

Remember, we can do anything to an equation as long as you do it to both sides
and distributive proeprty, reversed
ab+ac=a(b+c)
xm=x+z
minus x from both sides
xm-x=z
xm-1x
undistribute x
x(m-1)=z
divide both sides by (m-1)
Answer:
P(57 < X < 69) = 0.1513
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:

Find P(57 < X < 69):
This is the pvalue of Z when X = 69 subtracted by the pvalue of Z when X = 57. So
X = 69



has a pvalue of 0.9564
X = 57



has a pvalue of 0.8051
0.9564 - 0.8051 = 0.1513
P(57 < X < 69) = 0.1513
Answer: r = 3
Step-by-step explanation:
Step 1: Cross-multiply.
2r = 12/18
(2)*(18)=12*r
36=12r
Step 2: Flip the equation.
12r=36
Step 3: Divide both sides by 12.
12r/12 = 36/12
r = 3