The answer is B. 13.9. Since M is the midpoint, it splits the line into 2 equal parts.
27.8 / 2 = 13.9
This is pretty simple once you get used to this
First set it equal to the original and the negative one
(>_) is the bigger and equal to part
4x+5>_45 or 4x+5>_-45
Then solve for x for both
4x>_40. 4x>_-50
X>_10 X>_-25/2
Given:
μ = 89 ng/ml, population mean
σ = 23 ng/ml, population standard deviation
Random variable, x = 100
To test P(x < 100), calculate the z-score.
z = (x-μ)/σ = (100 - 89)/23 = 0.4783
From standard tables, obtain
P(x < 100) = 0.6838 = 68.4%
Answer: 68.4%
