Sample Test 4
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the
question.
Classify the hypothesis test as lower-tailed, upper-tailed, or two-sided.
1) In the past, the mean running time for a certain type of flashlight battery has been 8.3 hours. The
manufacturer has introduced a change in the production method and wants to perform a
hypothesis test to determine whether the mean running time has changed as a result.
A) Two-sided
B) Upper-tailed
C) Lower-tailed
Write the null and alternative hypotheses you would use to test the following situation.
2) At a local university, only 62% of the original freshman class graduated in four years. Has this
percentage changed?
A) H0 : p = 0.62
1)
2)
HA: p ≠ 0.62
B) H0 : p ≠ 0.62
HA: p = 0.62
C) H0 : p = 0.62
HA: p < 0.62
D) H0 : p < 0.62
HA: p = 0.62
E) H0 : p < 0.62
HA: p > 0.62
Construct the requested confidence interval from the supplied information.
3) A sample of 81 statistics students at a small college had a mean mathematics ACT score of 26
with a standard deviation of 6. Find a 95% confidence interval for the mean mathematics ACT
score for all statistics students at this college.
A) (25.3, 26.7)
3)
B) (25.9, 26.1)
C) (78.6, 83.4)
D) (25.3, 26.1)
E) (24.7, 27.3)
Determine the margin of error in estimating the population parameter.
4) Based on a sample of 39 randomly selected years, a 90% confidence interval for the mean annual
precipitation in one city is from 42.8 inches to 45.2 inches.
A) 2.4 inches
B) 1.2 inches
C) 0.10 inches
D) 0.32 inches
E) Not enough information is given.
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4)
5) The mean number of pets per household is 3.25 with standard deviation 1.3. A sample
of 59 households is drawn. Find the 74th percentile of the sample mean.
A) 3.36
B) 3.86
C) 4.11
D) 2.70
5)
6) For a particular diamond mine, 82% of the diamonds fail to qualify as "gemstone
grade". A random sample of 90 diamonds is analysed. Find the probability that the
proportion of the sample diamonds that fail to qualify as gemstone grade is between
0.78 and 0.88.
A) 0.1611
B) 0.8389
C) 0.9306
D) 0.7695
6)
7) The three confidence intervals below were constructed from the same sample. One of
them was computed at a confidence level of 90%, another at a confidence level of 95%,
and another at a confidence level of 98%.
7)
Which is the confidence level at 98%?
A) 36.5 < μ < 49.5
C) 37.6 < μ < 48.4
B) cannot be determined
D) 38.4 < μ < 47.6
8) A new organic pest control formula is being tested on potato plants to see whether it
can reduce the level of potato beetle infestation. The mean number of beetles per
untreated plant is 5. It is hoped that the new formula may reduce this infestation rate.
State the appropriate null and alternate hypotheses.
A) H0: μ = 5, H1: μ ≠ 5
B) H0: μ = 5, H1: μ < 5
C) H0: μ < 5, H1: μ = 5
D) H0: μ < 5, H1: μ > 5
8)
Use the given degree of confidence and sample data to construct a confidence interval for the population proportion.
9) When 293 college students are randomly selected and surveyed, it is found that 114 own a car.
9)
Construct a 99% confidence interval for the percentage of all college students who own a car.
A) (17.4%, 60.4%)
B) (32.3%, 45.5%)
C) (31.6%, 46.2%)
D) (34.2%, 43.6%)
E) (33.3%, 44.5%)
10) A study involves 634 randomly selected deaths, with 29 of them caused by accidents. Construct a
98% confidence interval for the percentage of all deaths that are caused by accidents.
A) (3.4%, 5.8%)
B) (2.64%, 6.50%)
C) (2.95%, 6.20%)
D) (3.21%, 5.94%)
E) (2.43%, 6.71%)
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10)
11) At a cell phone assembly plant, 81% of the cell phone keypads pass inspection. A
random sample of 97 keypads is analysed. Find the probability that more than 85% of
the sample keypads pass inspection.
A) 0.8577
B) 0.1587
C) 0.1423
D) 0.8413
Find the margin of error for the given confidence interval.
12) In a survey of 5100 T.V. viewers, 40% said they watch network news programs. Find the margin
of error for this survey if we want 95% confidence in our estimate of the percent of T.V. viewers
who watch network news programs.
A) 1.34%
B) 1.76%
C) 1.54%
D) 1.01%
Interpret the confidence interval.
13) How much fat do reduced fat cookies typically have? You take a random sample of 51
reduced-fat cookies and test them in a lab, finding a mean fat content of 4.2 grams. You calculate
a 95% confidence interval and find that the margin of error is ±0.8 grams.
A) 95% of the cookies in the sample had between 3.4 and 5 grams of fat.
11)
12)
13)
B) 95% of reduced fat cookies have between 3.4 and 5 grams of fat.
C) We are 95% sure that the average amount of fat in the cookies in this study was between 3.4
and 5 grams.
We are 95% confident that the mean fat in all cookies is between 3.4 and 5 grams.
D)
E) You are 95% confident that the mean fat in reduced fat cookies is between 3.4 and 5 grams
of fat.
14) A college admissions officer takes a simple random sample of 80 entering freshmen
and computes their mean mathematics SAT score to be 469. Assume the population
standard deviation is σ = 95.
14)
Construct a 90% confidence interval for the mean mathematics SAT score for the
entering freshmen class.
A) (455, 483)
B) (374, 564)
C) (467, 471)
D) (452, 486)
15) A certain car model has a mean gas mileage of 29 miles per gallon (mpg) with a
standard deviation 5 mpg. A pizza delivery company buys 38 of these cars. What is the
probability that the average mileage of the fleet is greater than 27.8 mpg?
A) 0.8599
B) 0.0465
C) 0.9306
D) 0.9535
15)
16) A sample of size 70 will be drawn from a population with mean 24 and standard
deviation 10. Find the probability that x will be between 22 and 25.
A) 0.7326
B) 0.2005
C) 0.0475
D) 0.7521
16)
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Answer Key
Testname: SAMPLE TEST 4 SPRING 2017
1) A
2) A
3) E
4) B
5) A
6) D
7) A
8) B
9) C
10) B
11) B
12) A
13) E
14) D
15) C
16) D
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