We need to find the area under the standard normal curve that is to the right of 66.
Various ways of doing this include the following:
1) Calculator: normalcdf(66, 10000, 100, 15) = 0.988, or 98.8%
2) z-scores (using a published table of z scores)
66 - 100
a) Find the z score corresponding to 66. It is z = -------------- = -2.27
15
b) Find the area under the st. normal curve to the left of z=-2.27 (it is 0.012). Subtract that area from the total area, 1.000. The result will be the answer to this question.
0.84(because 20% of the observations are about 0.84)
You've found the 80th percentile! The 80th percentile of the standard normal distribution is 0.84. That's because 80% of the observations fall below 0.84. (Note: The 80th percentile of every normal distribution is 0.84 times the standard deviation above the mean.)
Answer: the answer should be B
Step-by-step explanation:
