Review Exam on Statistics

What is the main purpose of inferential statistics?

• Summarize data

• Organize data

• Draw conclusions about a population

• Classify data into categories

Which of the following is a qualitative variable?

• Height

• Gender

• Weight

• Temperature

A variable that can take on any value within a range is called:

• Qualitative

• Quantitative

• Discrete

• Continuous

Which of the following is a discrete random variable?

• The weight of newborn babies

• The number of students in a classroom

• The height of basketball players

• The temperature of boiling water

If a fair die is rolled, what is the probability of rolling a 4?

• 1/6

• 1/4

• 1/3

• ½

Which of the following is not a characteristic of a probability distribution?

• The probabilities add up to 1

• Each probability is between 0 and 1

• Some probabilities can be negative

• It represents all possible outcomes

Convert a z-score of -1.5 to the corresponding value if the mean is 100 and the standard deviation is 20.

• 70

• 80

• 90

• 95

A factory produces light bulbs with a mean lifespan of 1200 hours and a standard deviation of 200 hours. What proportion of bulbs last less than 1000 hours? (Use z-tables for reference.)

• 0.1587

• 0.2410

• 0.3085

• 0.3413

Construct a normal curve for a distribution with μ = 50 and σ = 10. Indicate the region between z-scores of -1 and 1.

• Approximately 68%

• Approximately 75%

• Approximately 80%

• Approximately 85%

If the mean score of an exam is 85 and the standard deviation is 5, what is the probability of randomly selecting a score less than 75? (Use z-tables for reference.)

• 0.0013

• 0.023

• 0.0505

• 0.1587