For the following data set, calculate the percentage of data points that fall within one standard deviation of the mean, and compare the result to the expected percentage of a normal distribution. {70, 85, 84, 83, 96, 74, 66, 99, 84, 81} a. 50%; this percentage is lower than expected in a normal distribution. b. 60%; this percentage is lower than expected in a normal distribution. c. 70%; this percentage is close to the expected percentage in a normal distribution. d. 80%; this percentage is higher than expected in a normal distribution.

B.

Step-by-step explanation:

mean of {70, 85, 84, 83, 96, 74, 66, 99, 84, 81} is 82.2

population standard deviation is 9.8367

sample standard deviation is 10.369

Problem says nothing about random sample from a population, so the given values must be the whole population, so standard deviation is 9.8367 and not 10.369.

range for "one sigma" is 82.2-9.8 to 82.2+9.8 = 72.4 to 92.0

two data points are below, two are above. that is 40% of 10 data points outside, 60% inside.

Answer is B

2 over 5

step-by-step explanation:

the 2: 3 ratio is the length of the ac segment to the cb segment total length. this implies that the ratio between segment ac length and segment ab length is 2: 5. point c is 2/5 from a to b, so the required fraction is 2/5.

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step-by-step explanation: