Statistics MCQs –Continuous Distributions Part 8

141. In a large statistics class the heights of the students are normally distributed with a mean of 172cm and a variance of 25cm2. What proportion of students are between 175cm and 185cm in height?

a. 0.954

b. 0.601

c. 0.718

d. 0.883

e. 0.270

Answer: E

142. A statistical analysis of long-distance telephone calls indicates that the length of these calls is normally distributed with a mean of 240 seconds and a standard deviation of 40 seconds. What proportion of calls last less than 180 seconds or more than 300 seconds?

a. 0.911

b. 0.034

c. 0.134

d. 0.067

e. 0.548

Answer: C

143. A bakery finds that the average weight of its most popular package of cookies is 32.06g with a standard deviation of 0.10g. Assuming that the weight of the package of cookies follows a normal distribution, what portion of cookie packages will weigh less than 31.90 g or more than 32.30 g?

a. 0.06

b. 0.24

c. 0.78

d. 0.01

e. 0.00

Answer: A

144. A statistical analysis of long-distance telephone calls indicates that the length of these calls is normally distributed with a mean of 240 seconds and a standard deviation of 40 seconds. What proportion of calls lasts less than 180 seconds?

a. 0.214

b. 0.094

c. 0933

d. 0.466

e. 0.067

Answer: E

145. In a large statistics class the heights of the students are normally distributed with a mean of 172cm and a variance of 25cm2. What is the probability that a randomly selected student from this class will be taller than 180cm?

a. 0.055

b. 0.655

c. 0.274

d. 0.919

e. 0.992

Answer: A

146. In a large statistics class the heights of the students are normally distributed with a mean of 172cm and a variance of 25cm2. What is the probability that a randomly selected student from this class will be taller than 170cm?

a. 0.055

b. 0.655

c. 0.274

d. 0.919

e. 0.992

Answer: B

147. In a large statistics class the heights of the students are normally distributed with a mean of 172cm and a variance of 25cm2. What is the probability that a randomly selected student from this class will be taller than 175cm?

a. 0.055

b. 0.655

c. 0.274

d. 0.919

e. 0.992

Answer: C

148. In a large statistics class the heights of the students are normally distributed with a mean of 172cm and a variance of 25cm2. What is the probability that a randomly selected student from this class will be taller than 165cm?

a. 0.055

b. 0.655

c. 0.274

d. 0.919

e. 0.992

Answer: D

149. In a large statistics class the heights of the students are normally distributed with a mean of 172cm and a variance of 25cm2. What is the probability that a randomly selected student from this class will be taller than 160cm?

a. 0.055

b. 0.655

c. 0.274

d. 0.919

e. 0.992

Answer: E

150. Using the standard normal table, the sum of the probabilities to the right of z = 2.18 and to the left of z = -1.75 is:

a. 0.4854

b. 0.4599

c. 0.0146

d. 0.0401

e. 0.0547

Answer: E

151. The time until first failure of a brand of inkjet printers is normally distributed with a mean of 1500 hours and a standard deviation of 200 hours. What proportion of printers fails before 1000 hours?

a. 0.0062

b. 0.0668

c. 0.8413

d. 0.0228

e. 0.6915

Answer: A

152. The time until first failure of a brand of inkjet printers is normally distributed with a mean of 1500 hours and a standard deviation of 200 hours. What proportion of printers fails before 1200 hours?

a. 0.0062

b. 0.0668

c. 0.8413

d. 0.0228

e. 0.6915

Answer: B

153. The time until first failure of a brand of inkjet printers is normally distributed with a mean of 1500 hours and a standard deviation of 200 hours. What proportion of printers fails before 1700 hours?

a. 0.0062

b. 0.0668

c. 0.8413

d. 0.0228

e. 0.6915

Answer: C

154. The time until first failure of a brand of inkjet printers is normally distributed with a mean of 1500 hours and a standard deviation of 200 hours. What proportion of printers fails before 1100 hours?

a. 0.0062

b. 0.0668

c. 0.8413

d. 0.0228

e. 0.6915

Answer: D

155. The time until first failure of a brand of inkjet printers is normally distributed with a mean of 1500 hours and a standard deviation of 200 hours. What proportion of printers fails before 1600 hours?

a. 0.0062

b. 0.0668

c. 0.8413

d. 0.0228

e. 0.6915

Answer: E

156. Student marks for a first-year Statistics class test follow a normal distribution with a mean of 63% and a standard deviation of 7%. What is the probability that a randomly selected student who wrote the test got more than 75%?

a. 0.043

b. 0.388

c. 0.159

d. 0.666

e. 0.968

Answer: A

157. Student marks for a first-year Statistics class test follow a normal distribution with a mean of 63% and a standard deviation of 7%. What is the probability that a randomly selected student who wrote the test got more than 65%?

a. 0.043

b. 0.388

c. 0.159

d. 0.666

e. 0.968

Answer: B

158. Student marks for a first-year Statistics class test follow a normal distribution with a mean of 63% and a standard deviation of 7%. What is the probability that a randomly selected student who wrote the test got more than 70%?

a. 0.043

b. 0.388

c. 0.159

d. 0.666

e. 0.968

Answer: C

159. Student marks for a first-year Statistics class test follow a normal distribution with a mean of 63% and a standard deviation of 7%. What is the probability that a randomly selected student who wrote the test got more than 60%?

a. 0.043

b. 0.388

c. 0.159

d. 0.666

e. 0.968

Answer: D

160. Student marks for a first-year Statistics class test follow a normal distribution with a mean of 63% and a standard deviation of 7%. What is the probability that a randomly selected student who wrote the test got more than 50%?

a. 0.043

b. 0.388

c. 0.159

d. 0.666

e. 0.968

Answer: E