Question

In: Statistics and Probability

A random sample of 40 students is collected and the number of credit hours taken is...

A random sample of 40 students is collected and the number of credit hours taken is recorded. The sample mean is computed to be 12.5 hours with a standard deviation of 3 hours. Construct a 95% confidence interval for the mean credit hours taken. Follow 4-step procedure.

Expert Solution

Solution :

Given that,

Point estimate = sample mean = = 12.5

Population standard deviation = =3

Sample size n =40

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.96 ( Using z table )

Margin of error = E = Z/2 * ( / $\sqrt$ n)
= 1.96 * (3 / $\sqrt$ 40 $\sqrt$ )

= 0.93
At 95% confidence interval mean
is,

- E < < + E

12.5- 0.93 < < 12.5+ 0.93

(11.57,13.43 )

orchestra answered 1 year ago

Data were collected on number of credit hours earned from a random sample of 40 JMU...

Data were collected on number of credit hours earned from a random sample of 40 JMU students. The mean was 57.2 and the standard deviation was 8.9. Conduct a test to determine whether the true mean number of credit hours earned differs from 55.0, allowing a Type I error rate of 0.05. Assume that the distribution of the number of credit hours earned is normal. Show your full work. You may not use your calculator’s built-in function.

Researchers have collected data from a random sample of six students on the number of hours...

Researchers have collected data from a random sample of six students on the number of hours spent studying for an exam and the grade received on the exam as given in Table 6.5. Table 6.5 Observation Grade Number of Hours Studying 1 85 8 2 73 10 3 95 13 4 77 5 5 68 2 6 95 12 d) Find and interpret a 90% confidence interval for the true population slope parameter.

A random sample of 40 students taken from a university showed that their mean GPA is...

A random sample of 40 students taken from a university showed that their mean GPA is 2.94 and the standard deviation of their GPAs is .30. Construct a 99% confidence interval for the mean GPA of all students at this university

3. If a random sample of 53 students was asked for the number of semester hours...

3. If a random sample of 53 students was asked for the number of semester hours they are taking this semester. The sample standard deviation was found to be s = 4.7 semester hours. How many more students should be included in the sample to be 99% sure that the sample mean x is within 1 semester hour of the population mean  for all students at this college? i. A marketer is trying two different sales pitches to sell...

1) A random sample of the number of hours worked by 40 employees has a mean...

1) A random sample of the number of hours worked by 40 employees has a mean of 29.6 hours worked. Assume the population standard deviation is 7.9 hours. a. Using a 95% confidence level, find the margin of error, E, for the mean number of hours worked. 2) In a study of 265 subjects, the average score on the examination was 63.8. Assume σ = 3.08. a. What is a 95% confidence interval for ? 3) A college admissions director...

Data was collected on annual personal time (in hours) taken by a random selection of 50...

Data was collected on annual personal time (in hours) taken by a random selection of 50 women and 55 men employed by a medium-sized company. We know that the data for women and men is normally distributed. The Human Resources Department believes that the amount of personal time used by women is less than the amount of personal time used by men. The sample of women took an average of 25 hours of personal time with a standard deviation of...

The Nellie Mae organization found random sample of 100 students taken in 2004, average credit card...

The Nellie Mae organization found random sample of 100 students taken in 2004, average credit card balance = $2169. Suppose sample standard deviation of the credit card balances = $1000. Perform a test to test if the average credit card debt exceeds $2000. a) what is the population, variable, parameter b) does CLT hold c) state hypothesis, H0 = , HA : d) calculate test stat e) find p-value range f) make decision at .05 significance level and write...

A random sample of American children was taken to estimate the total number of hours they spend watching cartoons in an average week.

0 3 1 20 9 5 10 1 10 4 14 2 4 4 5 A random sample of American children was taken to estimate the total number of hours they spend watching cartoons in an average week. The responses above were chosen from a simple random sample of 15 children and the data was normally distributed. Create a 98% confidence interval for the mean number of hours American children spend watching cartoons in one week. 1st: Identify point estimate ...

In a local university, 40% of the students live in the dormitories. A random sample of...

In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The probability that the sample proportion (the proportion living in the dormitories) is at least 0.30 is Select one: a. 0.0336 b. 0.9664 c. 0.9328 d. 0.4664

Students in Physics and Chemistry a random sample was taken from 20 students in Physics, from...

Students in Physics and Chemistry a random sample was taken from 20 students in Physics, from which an average of 3 hours per week was obtained with a deviation. typical of 2.5 hours, and another sample of 30 independent chemistry students from the previous one, which presented an average of 2.8 hours, with a deviation. typical 2.7h. Assuming that the weekly study hours of the two types of students follow a normal distribution, (a) Calculate a 95% confidence interval for...