Statistics H. - Intro to Percentiles and Normal Curves

Question 1

What % of observations in a normal distribution lie within two standard deviations of the mean?

Accepted Answer

≈ 95%

Question 2

Given N(100, 1), what percent of observation fall between 70 and 130?

Accepted Answer

≈ 99.7%

Question 3

Given N(100, 10), what percent of observations are within 22 of the mean?

Accepted Answer

≈ 97%

Question 4

Given N(100, 10), what is the lowest observation that falls in the top 15%?

Accepted Answer

≈ 110

Question 5

Given N(100, 10), what observation lies at the 95th percentile?

Accepted Answer

≈ 120

Question 6

If a distribution is skewed to the left, then which of the following is true?

Accepted Answer

mean < median

Question 7

If 150 people take a test and 9 score better than you, what is your %ile?

Accepted Answer

≈ 94th %ile

Question 8

Given N(100, 10), what percent of observations are less than 114?

Accepted Answer

≈ 92%

Question 9

If 150 people take a test and you score better than or equal to 125 of them, what is your %ile?

Accepted Answer

≈ 83rd %ile

Question 10

Given N(100, 10), what percent of observations are less than 90?

Accepted Answer

≈ 16%

Questions 10