Deck 17: Confidence Intervals for Means

Question 1

Based on a sample of 30 randomly selected years, a 90% confidence interval for the mean annual precipitation in one city is from 48.7 inches to 51.3 inches.Find the margin of error.

A)0.39 inches
B)0.10 inches
C)2.6 inches
D)1.3 inches
E)There is not enough information to find the margin of error.

Answer 1

D

Question 2

Answer 2

C

Question 3

Answer 3

C

Question 4

The amounts (in ounces) of juice in eight randomly selected juice bottles are:

Question 5

Using the t-tables, software, or a calculator, estimate the critical value of t for the given confidence interval and degrees of freedom: 80% confidence interval with df = 11

A)1.372
B)2.718
C)1.280
D)1.356
E)1.363

Question 6

Using the t-tables, software, or a calculator, estimate the critical value of t for the given confidence interval and degrees of freedom: 90% confidence interval with df = 4.

A)1.645
B)1.533
C)2.353
D)2.132
E)4.604

Question 7

Question 8

Based on a sample of size 49, a 95% confidence interval for the mean score of all students, μ, on an aptitude test is from 59.2 to 64.8.Find the margin of error.

A)5.6
B)0.78
C)0.05
D)2.8
E)There is not enough information to find the margin of error.

Question 9

Question 10

Question 11

Question 12

Question 13

Thirty randomly selected students took the calculus final.If the sample mean was 95 and the standard deviation was 6.4, construct a 99% confidence interval for the mean score of all
Students.

A)(92.12, 97.88)
B)(91.78, 98.22)
C)(93.01, 98.21)
D)(93.01, 96.99)
E)(91.79, 98.21)

Question 14

A sociologist develops a test to measure attitudes about public transportation, and 27 randomly selected subjects are given the test.Their mean score is 76.2 and their standard
Deviation is 21.4.Construct the 95% confidence interval for the mean score of all such
Subjects.

A)(64.2, 83.2)
B)(64.2, 88.2)
C)(74.6, 77.8)
D)(69.2, 83.2)
E)(67.7, 84.7)

Question 15

Question 16

Question 17

A certain population is strongly skewed to the right.We want to estimate its mean, so we will collect a sample.Which should be true if we use a large sample rather than a small one?
I)The distribution of our sample data will be closer to normal.
II)The sampling model of the sample means will be closer to normal.
III)The variability of the sample means will be greater.

A)I only
B)II only
C)III only
D)I and III only
E)II and III only