Question
In: Statistics and Probability
In a random sample of 120 car batteries produced by a special method, the sample average...
In a random sample of 120 car batteries produced by a special
method, the sample average lifetime was 135 hours and the sample
standard deviation was 12 hours. An engineer claims that the mean
lifetime is between 132.452 and 137.548 hours. Assume data is
normally distributed.
(a) What level of confidence can this statement be made
with?
(b) Create a confidence interval for the population variance
and explain how you did it. State your conclusion.
Solutions
orchestra answered 1 year agoRelated Solutions
The capacities (in ampere-hours) were measured for a sample of 120 batteries. The average was 178...
The capacities (in ampere-hours) were measured for a sample of
120 batteries. The average was 178 and the standard deviation was
12.
a.)
Find a
95% lower confidence bound for the mean capacity of this type of
battery. Round the answer to two decimal places.
b.)
An
engineer claims that the mean capacity is greater than 175
ampere-hours. With what level of confidence can this statement be
made? Express the answer as a percent and round to two decimal
places.
A random sample of 120 observations produced a mean of ?⎯⎯⎯ =29.4 from a population with...
A random sample of 120 observations produced a mean of ?⎯⎯⎯
=29.4 from a population with a normal distribution and a standard
deviation ?=2.45.
(a) Find a 95% confidence interval for ?
___ ≤ ? ≤ ___
(b) Find a 90% confidence interval for ?
___ ≤ ? ≤ ___
(c) Find a 99% confidence interval for ?μ
___ ≤ ? ≤ ___
Question 4 [25] The Zambezi car battery manufacturer claims that the average lifespan of batteries produced...
Question 4 [25]
The Zambezi car battery manufacturer claims that the average
lifespan of batteries produced by his firm is at least 30 months.
The rival manufacture the Rehoboth batteries disagree and took
random sample of 100 Zambezi car batteries and recorded a mean of
31.7 months and a standard deviation of 8 months. (Show all your
works)
Determine the following:
a) The null and alternative hypotheses
b) The test statistic value.
c) The critical statistics value at 99% confidence...
5) In a simple random sample of 59 electronic components produced by a certain method, the...
5) In a simple random sample of 59 electronic components
produced by a certain method, the mean lifetime was 1,114 hours.
Assume the component lifetimes are normally distributed with
population standard deviation 55 hours. What is the upper bound of
the 95% confidence interval for the mean lifetime of the
components? Round to nearest integer.
6) Efficiency experts study the processes used to manufacture
items in order to make them as efficient as possible. One of the
steps used to...
A random sample of 64 observations produced the following summary statistics: average = 0.36 and variance...
A random sample of 64 observations produced the
following
summary statistics: average = 0.36 and variance =
0.034.
a. Test the null hypothesis that m =0 .397 against
the alternative
hypothesis, using a = 0.10.
Interpret the result.
A random sample of 1515 teachers from Winnipeg produced an average annual salary of $35,270 with...
A random sample of 1515 teachers from Winnipeg produced an
average annual salary of $35,270 with a standard deviation of
$3,256. A random sample of 2020 teachers from Brandon produced an
average salary of $32,268 with a standard deviation of $2,532
a) (7 points) Using critical value approach test at
2%significance level whether the true mean annual salaries for all
teachers in both cities are different? State the assumption(s)
required for the test.
b) (3 points) Construct a 98% confidence...
A random sample of 10 batteries is obtained. It is determined that the mean life is...
A random sample of 10 batteries is obtained. It is determined
that the mean life is 5 hours, with a sample standard deviation of
1 hour.
A)Find the 95% confidence interval (CI) for the unknown mean of
the population.
B)Interpret the meaning of the confidence interval.
A manufacturer of car batteries claims that the life of the company’s batteries in years is...
A manufacturer of car batteries claims that the life of the
company’s batteries in years is approximately normally distributed
with a population variance of 0.81. A random sample of 10 of these
batteries has a variance of 1.44. Construct a 95% C.I. for .
Use and to construct the interval.
The following sample data represents the life cycle in months of two car batteries: A: 62,...
The following sample data represents the life cycle in months of
two car batteries:
A: 62, 59, 59, 51, 55, 53, 58, 49, 61, 55
B: 45, 50, 47, 46, 48, 46, 45, 46, 51, 49, 47, 49, 48, 45,
57
Is the variation in life cycle the same between batteries at
lambda=.05? Are the means the same as well at lambda=.05? Which
battery would you choose and why?
The following sample data represents the life cycle in months of two car batteries: A: 62,...
The following sample data represents the life cycle in months of
two car batteries:
A: 62, 59, 59, 51, 55, 53, 58, 49, 61, 55
B: 45, 50, 47, 46, 48, 46, 45, 46, 51, 49, 47, 49, 48, 45,
57
Is the variation in life cycle the same between batteries at
lambda=.05? Are the means the same as well at lambda=.05? Which
battery would you choose and why?
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