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WEEK 1 – PRACTICE – NORMAL DISTRIBUTION
Multiple Choice Questions 1.
The area under the standard normal curve between -2.0 and -1 is a. 0.0228 b. 0.1359 c. 0.4772 d. 0.3413
2. The time it takes for a dose of a certain drug to be effective as a sedative on lab animals is normally
distributed with a mean of 1 hour and a standard deviation of 0.1 hour. If X represents this time, then P(X > 1.1) is a. 0.0000 b. 0.5000 c. 0.3643 d. 0.1587
3. The probability that an observation taken from a standard normal population will be between -1.96 and 1.28 is a. 0.0753 b. - 0.0753 c. 0.1253 d. 0.8747 4. The value of such that is a. 1.28 b. 0.00 c. 0.1003 d. None of the above
5. The area under the standard normal curve between z = - 1.68 and z = 0 is a. 0.4535 b. 0.0465 1 lOMoARcPSD|364 906 32 c. 0.9535 d. – 0.4535
6. If IQ scores are normally distributed with a mean of 100 and a standard deviation of 20, then the
probability of a person’s having an IQ score of at least 130 a. is 0.4332 b. is 0.5000 c. does not exist d. is 0.0668
7. A bank finds that the balances in its saving accounts are normally distributed with a mean of $500
and a standard deviation of $50. The probability that a randomly selected account has a balance of more than $600 is a. 0.4772 b. 0.0228 c. 0.9772 d. 0.0000
8. The waiters in a restaurant receive an average tip of $20 per table with a standard deviation of $5.
The amounts of tips are normally distributed, and a waiter feels that he has provided excellent
service if the tip is more than $25. The probability that a waiter has provided excellent service to a table is a. 0.1587 b. 0.8413 c. 0.8000 d. 0.6587
9. Suppose family incomes in a town are normally distributed with a mean of $1,200 and a standard
deviation of $600 per month. The probability that a given family has an income over $2,000 per month is a. 0.0918 b. 0.9082 c. 0.4082 d. 0.5918 2 lOMoARcPSD|364 906 32
10. Suppose family incomes in a town are normally distributed with a mean of $1,200 and a standard
deviation of $600 per month. The probability that a given family has an income between $1,000 and $2,050 per month is a. 0.4585 b. 0.7001 c. 0.4222 d. 0.5515 3 lOMoARcPSD|364 906 32 4