Mu = mean = 25
sigma = standard deviation = 5.5
Compute the z score for x = 19.5
z = (x-mu)/sigma
z = (x-25)/5.5
z = (19.5-25)/5.5
z = -1
Compute the z score for x = 30.5
z = (x-mu)/sigma
z = (x-25)/5.5
z = (30.5-25)/5.5
z = 1
Therefore, P(19.5 < X < 30.5) is the same as P(-1 < Z < 1) which asks "what is the area under the standard normal curve from z = -1 to z = 1?"
By the Empirical Rule, roughly 68% of the normal distribution is between z = -1 and z = 1. In other words, 68% of the normally distributed population is within one standard deviation. The z-scores help keep track how far you are in terms of standard deviations.
Final Answer: Choice B) 68%
Answer:
-9x
Step-by-step explanation:
Without the confusing parentheses, this "polynomial" becomes -8x + x -2x. If we take 2 away from -8, it becomes -10. If we add a positive x, it becomes -9x. Therefore, the answer is (the monomial) -9x.
12 is 60% of 20. You can make 60% into a fraction (60/100) and set that fraction equal to 12/x. You then cross multiply (12*100 and 60*x) to get 1200=60x. You then divide both sides by 60 to get x, which equals 20.
