A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least
753
hours. A random sample of
20
light bulbs has a mean life of
732
hours. Assume the population is normally distributed and the population standard deviation is
61
hours. At
α=0.02,
do you have enough evidence to reject the manufacturer's claim? Complete parts (a) through (e).
(a) Identify the null hypothesis and alternative hypothesis.
A.
H0:
μ<732
(claim)
Ha:
μ≥732
B.
H0:
μ≠753(claim)
Ha:
μ=753
C.
H0:
μ=732
Ha:
μ≠732
(claim)
D.
H0:
μ≤732
Ha:
μ>732
(claim)
E.
H0:
μ>753
Ha:
μ≤753
(claim)
F.
H0:
μ≥753
(claim)
Ha:
μ<753
(b) Identify the critical value(s). Use technology.
z0=nothing
(Use a comma to separate answers as needed. Round to two decimal places as needed.)
Identify the rejection region(s). Choose the correct answer below.
A.-404z
Reject H0.
Reject H0.
Fail to reject H0.
A normal curve is over a horizontal z-axis labeled from negative 4 to 4 in increments of 1 and is centered on 0. Vertical line segments extend from the horizontal axis to the curve at negative 2.1 and 2.1. The area under the curve to the left of negative 2.1 is shaded and the area under the curve to the right of 2.1 are both shaded one color and labeled Reject Upper H 0.The area under the curve between negative 2.1 and 2.1 is shaded another color and labeled Fail to reject Upper H 0.
B.-404z
Reject H0.
Fail to reject H0.
A normal curve is over a horizontal z-axis labeled from negative 4 to 4 in increments of 1 and is centered on 0. A vertical line segment extends from the horizontal axis to the curve at 2.1. The area under the curve to the right of 2.1 is shaded one color and labeled Reject Upper H 0. The area under the curve to the left of 2.1 is shaded another color and labeled Fail to reject Upper H 0.
C.-404z
Reject H0.
Fail to reject H0.
A normal curve is over a horizontal z-axis labeled from negative 4 to 4 in increments of 1 and is centered on 0. A vertical line segment extends from the horizontal axis to the curve at negative 2.1. The area under the curve to the left of negative 2.1 is shaded one color and labeled Reject Upper H 0. The area under the curve to the right of negative 2.1 is shaded another color and labeled Fail to reject Upper H 0.
(c) Identify the standardized test statistic. Use technology.
z=nothing
(Round to two decimal places as needed.)
(d) Decide whether to reject or fail to reject the null hypothesis, and (e) interpret the decision in the context of the original claim.
A.
Reject
H0.
There
is
sufficient evidence to reject the claim that mean bulb life is at least
753
hours.
B.
Fail to reject
H0.
There
is
sufficient evidence to reject the claim that mean bulb life is at least
753
hours.
C.
Reject
H0.
There
is not
sufficient evidence to reject the claim that mean bulb life is at least
753
hours.
D.
Fail to reject
H0.
There
is not
sufficient evidence to reject the claim that mean bulb life is at least
753
hours.
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