Question
In: Statistics and Probability
The director of admissions at a large university advises parents of incoming students about the cost...
The director of admissions at a large university advises parents of incoming students about the cost of textbooks during a typical semester. He selected a sample of 100 students and recorded their textbook expenses for the semester. He then calculated a sample mean of $675.60 and a sample standard deviation of $45.20. You may assume that the distribution of textbook expenses is approximately normally distributed.
(a) Is there sufficient evidence that the population mean textbook expense per semester is above $665? You should justify your answer with a hypothesis test at the 5% significance level.
(b) Construct a 95% confidence interval estimate of the population mean textbook expense per semester.
Please do not include any image.
Solutions
orchestra answered 1 year agoRelated Solutions
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The director of admissions of a small college selected 120 students at random from the new...
The director of admissions of a small college selected 120
students at random from the new freshman class in a study to
determine whether a student’s grade point average (GPA) at the end
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GPA ACT ITS RP
3.897 21 122 99
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3.778 28 119 95
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2.962 32 113 85...
An admissions director wants to estimate the mean age of all students enrolled at a college....
An admissions director wants to estimate the mean age of all
students enrolled at a college. The estimate must be within 1 years
of the population mean. Assume the population of ages is normally
distributed and the population standard deviation is 9.5 years.
Determine the minimum sample size required to construct a 80%
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*in r studio file 4. The director of admissions of a small college selected 120 students...
*in r studio file
4. The director of admissions of a small college selected 120
students at random from the new freshman class in a study to
determine whether a student’s grade point average (GPA) at the end
of the freshman year (y) can be predicted from the ACT test score
(x). Estimate the simple linear regression of, y = β0 + β1x + ε,
using gpa.txt data and answer the following questions. (4
pts each)
(a) Report the least...
A college admissions director wishes to estimate the mean age of all students currently enrolled. In...
A college admissions director wishes to estimate the mean age of
all students currently enrolled. In a random sample of 81 students,
the mean age is found to be 20.51 years. From past studies, the
standard deviation of the population is known to be 2 years, and
the population is normally distributed. Construct a 99% confidence
interval of the population mean age. (Round off final answers to
two decimal places, if appropriate. Do not round off numbers taken
directly from...
A college admissions director wishes to estimate the mean age of all students currently enrolled. In...
A college admissions director wishes to estimate the mean age of
all students currently enrolled. In a random sample of 19 students,
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1. What is the critical value?
2. What is the standard deviation of the sample mean?
3....
A college admissions director wishes to estimate the mean age of all students currently enrolled. In...
A college admissions director wishes to estimate the mean age
of all students currently enrolled. In a random sample of 19
students, the mean age is found to be 22.4 years. From past
studies, the ages of enrolled students are normally distributed
with a standard deviation of 9.5 years. Construct a 90% confidence
interval for the mean age of all students currently enrolled.
1. what is the critical value ?
2. the margin of error?
A college admissions director wishes to estimate the mean age of all students currently enrolled. In...
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b. The standard deviation of the sample mean:
A large university is interested in learning about the average time it takes students to drive...
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used conduct a test of hypothesis. The goal was to determine if the
average travel time of all the university's students differed from
20 minutes. Use a...
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