Use Statdisk’s Normal probability distribution module to find the indicated probabilities.
Select Analysis >> Probability Distributions >> Normal. Values can be found by using the Cumulative Probability option. Remember that these probabilities correspond to cumulative areas to the left.
a) Given a population with a normal distribution, a mean of 0, and a standard deviation of 1, find the probability of a value less than 0.75.
b) Given a population with a normal distribution, a mean of 100, and a standard deviation of 15, find the probability of a value less than 83.
c) Given a population with a normal distribution, a mean of 120, and a standard deviation of 10, find the probability of a value greater than 135.
d) Given a population with a normal distribution, a mean of 98.6, and a standard deviation of 0.62, find the probability of a value between 97.0 and 99.0.
e) Given a population with a normal distribution, a mean of 150, and a standard deviation of 12, find the probability of a value between 147 and 160.
7.1 In 7.1, use Statdisk with the sample data and confidence level to construct the confidence interval estimate of the population proportion p. From a KRC Research poll in which respondents were asked if they felt vulnerable to identity theft: n = 1002, x = 531 who said “yes”. Use a 95% confidence level.
7.2 Sample Size for Proportion: You have been hired by the Ford Motor Company to do market research, and you must estimate the percentage of households in which a vehicle is owned.
How many households must you survey if you want to be 94% confident that your sample percentage has a margin of error of three percentage points?
a. Assume that a previous study suggested that vehicles are owned in 86% of households.
b. Assume that there is no available information that can be used to estimate the percentage of households in which a vehicle is owned.