A sample mean, sample size, and population standard deviation are

given. Use the one-mean z-test to perform the required hypothesis test at the given significance level. Use the critical -value approach.

= 25, n = 40, σ = 1.5, H0: μ = 23; Ha: μ ≠ 23, α = 0.05
z = 8.43; critical values = ±1.96; reject H0
z = 8.43; critical values = ±1.645; reject H0
z = 8.43; critical values = ±1.645; do not reject H0
z = 8.43; critical values = ±1.96; do not reject H0

A hypothesis test is to be performed. Determine the null and alternative hypotheses.

In the past, the mean running time for a certain type of flashlight battery has been  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.

H0: μ ≠ 8.1 hours
Ha: μ = 8.1 hours

H0: μ = 8.1 hours
Ha: μ ≠ 8.1 hours

H0: μ = 8.1 hours
Ha: μ > 8.1 hours

H0: μ ≥ 8.1 hours
Ha: μ = 8.1 hours

The lengths of human pregnancies are normally distributed with a mean of 268 days and a standard deviation of 15 days. What is the probability that a pregnancy lasts at least 300 days?

0.9834

0.0179

0.4834

0.0166

Determine the critical value(s) for a one-mean z-test.

A left-tailed test with α = 0.05 .
±1.96
±1.645
-1.96
-1.645

Find the indicated probability or percentage for the normally distributed variable.

The variable X is normally distributed.The mean is μ = 22.0 and the standard deviation is σ = 2.4.
Find P(19.7 < X < 25.3).

1.0847
0.7477
0.3370
0.4107

The graph portrays the decision criterion for a one-mean z-test. The curve in the graph is the normal curve for the test statistic under the assumption that the null hypothesis is true. Use the graph to solve the problem.

A graphical display of the decision criterion follows.

Determine the critical value(s).

α = 0.025

z ≤ -1.96

z = ±1.96

z = -1.96
A hypothesis test is to be performed. Determine the null and alternative hypotheses.

The recommended dietary allowance (RDA) of vitamin C for women is 75 milligrams per day. A hypothesis test is to be performed to decide whether adult women are, on average, getting less than the RDA of 75 milligrams per day.
H0: μ = 75 mg
Ha: μ < 75 mg
H0: μ = 75 mg
Ha: μ ≤ 75 mg
H0: μ > 75 mg
Ha: μ < 75 mg

H0: μ < 75 mg
Ha: μ = 75 mg
Find the indicated probability or percentage for the normally distributed variable.

The variable X is normally distributed. The mean is μ = 60.0 and the standard deviation is σ = 4.0.
Find P(X < 53.0).

0.0802
0.9599
0.5589
0.0401
A sample mean, sample size, and population standard deviation are given. Use the one-mean z-test to perform the required hypothesis test at the given significance level. Use the critical -value approach.

= 7.9, n = 18 , σ = 1.7, H0: μ = 10; Ha: μ < 10, α = 0.01

z = -5.24; critical value = 1.96; do not reject H0

z = -5.24; critical value = -1.96; reject H0

z = -5.24; critical value = -2.33; reject H0

z = -5.24; critical value = -2.33; do not reject H0

1 points
Classify the hypothesis test as two-tailed, left-tailed, or right-tailed.

The recommended dietary allowance (RDA) of vitamin C for women is 75 milligrams per day. A hypothesis test is to be performed to decide whether adult women are, on average, getting less than the RDA of 75 milligrams per day.

Two-tailed

Left-tailed

Right-tailed

1 points
Determine the critical value(s) for a one-mean z-test.

A two-tailed test with α = 0.08.

±2.575

±1.645

±1.764

±1.75

1 points
A hypothesis test is to be performed. Determine the null and alternative hypotheses.

A health insurer has determined that the “reasonable and customary” fee for a certain medical procedure is  They suspect that the average fee charged by one particular clinic for this procedure is higher than  The insurer wants to perform a hypothesis test to determine whether their suspicion is correct.

H0: μ = $1200
Ha: μ ≥ $1200

H0: μ = $1200
Ha: μ > $1200

H0: μ = $1200
Ha: μ < $1200

H0: μ > $1200
Ha: μ = $1200
A sample mean, sample size, and population standard deviation are given. Use the one-mean z-test to perform the required hypothesis test at the given significance level. Use the critical -value approach.

= 51, n = 45 , σ = 3.6, H0: μ = 50; Ha: μ > 50, α = 0.01

z = 1.86; critical value = 1.33; reject H0

z = 1.86; critical value = 2.33; reject H0

z = 0.28; critical value = 2.33; do not reject H0

z = 1.86; critical value = 2.33; do not reject H0
Classify the hypothesis test as two-tailed, left-tailed, or right-tailed.

In the past, the mean running time for a certain type of flashlight battery has been  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.

Two-tailed

Left-tailed

Right-tailed
Determine the critical value(s) for a one-mean z-test.

A right-tailed test with α = 0.03.

-1.88

2.17

1.88

-2.17, 2.17
Classify the hypothesis test as two-tailed, left-tailed, or right-tailed.

A psychologist has designed a test to measure stress levels in adults. She has determined that nationwide the mean score on her test is 26. A hypothesis test is to be conducted to determine whether the mean score for trial lawyers exceeds the national mean score.

Two-tailed

Left-tailed

Right-tailed
need answers for home work statitistics

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