Statistics STA 1103 - W17 In class Quiz 1 Feb 1, 2107 STUDENT NAME: _____________________________ STUDENT NUMBER: ______________________________ In Class Quiz #1 - Normal Distribution - 2.5% of your final mark Statistics STA 1103 - W17 1. Which description of a normal distribution is correct? a. b. c. d. In a normal distribution, the median is approximately equal to the mean. The mean of a normal distribution must be zero. The standard deviation of a normal distribution must be one. In a normal distribution, the median is unrelated to the mean. 2. In a normal distribution, what percentage of the area under the curve is within three standard deviations of the mean? a. b. c. d. 68% 50% 95% 99% 3. Consider a normal distribution with a mean of 20 and standard deviation of the mean of 6. 68% of its area is within: a. b. c. d. One standard deviation of the mean Two standard deviations of the mean Three standard deviations of the mean It depends on the value of the mode 4. In a standard normal distribution, the mean & standard deviation are which of the following: a. b. c. d. 1.0; 0.0 -1.0; 1.0 0.0; 1.0 0.0; -1.0 5. Consider a normal distribution with a mean of 5 and standard deviation of 4. Approximately, what proportion of the area lies between values of -3 and 13. a. b. c. d. 68% 95% 99% 50% 2017 LAMBTON COLLEGE IN TORONTO Statistics STA 1103 - W17 6. For a normal distribution with a mean of 20 and standard deviation of 2, what is the probability of finding a number greater than 26? a. b. c. d. 5.0% 2.5% 1.0% 0.15% 7. A random sample of 85 group leaders, supervisors, & similar personnel revealed that on the average a person spent 6.5 years on the job before being promoted. The standard deviation of the population was 1.7 years. Find the 95% confidence interval for the population mean. a. b. c. d. 6.99 and 7.99 4.15 and 7.15 6.14 and 6.86 6.49 and 7.49 8. A sample of 20 is selected from a population. What is the number of degrees of freedom used to determine the appropriate critical t-value? a. b. c. d. 20 19 21 18 9. A student wanted to quickly construct a 95% confidence interval for the average age of students in her statistics class. She randomly selected a sample of 9 students. Within the sample, the average age was 19.1 years with a standard deviation of 1.5 years. What is the 95% confidence interval for the population mean? a. b. c. d. [ 0.97, 3.27 ] [ 15.64, 22.56 ] [ 17.97, 20.23 ] [ 17.95, 20.25 ] 10. The t - distribution has a. a mean of zero and a standard deviation of one b. a mean of one and a standard deviation of one c. a mean of zero and a standard deviation that depends on the sample size d. a mean that depends on the sample size and a standard deviation of one 2017 LAMBTON COLLEGE IN TORONTO