Exam 4: The Normal Curve

A social work researcher constructed a measure of quality of life and obtained a distribution of scores on this measure from a randomly selected sample of elderly persons. The scores were normally distributed, with a mean of 45 and a standard deviation of 7. What is the probability that a randomly selected case from the sample will have a score less than 38?

Which two characteristics describe normal curve distribution?

What is the process for determining the area between two negative Z scores?

What is the lower limit of a probability?

Briefly explain the statistical meaning of the term "probability."

What is the value of the corresponding raw score if a Z score is 0?

A Z score of -0.5 means that the case's raw score is how much less than the sample mean?

What is the process for finding the area above a positive Z score or below a negative Z score?

For a sample of 100 nursing home residents where we assume blood pressure to be normally distributed, approximately how many people would be two standard deviations below the mean blood pressure?

If it rains 21 of 30 days in a month, what value represents the probability of rain occurring on a single day chosen at random from the month?

A researcher obtains a sample of 15 university students to conduct a study on physical strength and memorization ability. If the researcher selects one student at random from the sample, what is the probability that she will select a human being?

What is the process for obtaining the area between the scores when the Z scores of two tests' scores are +1.2 and +1.5?

What is the probability of rolling a 1 in a single toss of a six-sided die?

What property of the normal curve ensures that the area from the mean to -2 standard deviations is the same as the area from the mean to +2 standard deviations?

For a curve that is NOT normally distributed, what percentage of the area will be beyond ±1.5 standard deviations?

-Refer to Table 4.1. If a case is selected randomly from the distribution, what is the approximate probability that its value will be between 1.75 standard deviations above the mean and 2 standard deviations above the mean?

-Refer to Table 4.1. What percentage of a sample will be more than 1.5 standard deviations above the mean?

-Refer to Table 4.1. Approximately what proportion of the standard distribution's total area is found between 1.5 standard deviations above the mean and 2 standard deviations above the mean?

The mean score on a physiology test was 71, and the standard deviation of scores was 9. Assuming a normal distribution, what percentage of scores fell below a 60?

In what sense is the normal distribution a distribution of probabilities?