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# Statistics questions

### Resolved Question:

1. The hours of study and the final exam grades have this type of relationship: ŷ = 7.35(hours) + 34.62. Based on this linear regression equation, estimate the expected grade for a student spending 8 hours studying. Round your answer to two decimal places

2. At a drive through window of a bank it’s found that 10 customers get served every 15 minutes. The bank’s manage is interested in finding a way to increase the number of customers that can be served. He thought that knowing the probability of serving 12 customers per 15 minutes could be helpful to him in the decision making process. Choose the best answer of the following

3. Microfracture knee surgery has a 75% chance of success on patients with degenerative knees. The surgery is performed on 5 patients. Find the probability of the surgery being successful on 3 or 4 patients?

4. It has been recorded that 10 people get killed by shark attack every year. What is the probability of having 3 or 4 people get killed by shark attack this year?

5. The median teaching hours for a full time faculty at a state university is eight hours per week. What does this tell you about the typical teaching hours for full time faculty at that university?

6. Assuming that the data are normally distributed with a mean of 25 and a standard deviation of 1.25, what is the z-score for a value of 27?

7. The mean hours of Internet usage by adults in the US in claimed to be 25 hours per week. A hypothesis test is performed at a level of significance of 0.05 with a P-value of 0.08. Choose the best interpretation of the hypothesis test

8. A result of an entry level exam reveals that 22% of students fail that exam. In a hypothesis test conducted at a level of significance of 2%, a P-value of 0.045 was obtained. Choose the best interpretation of the hypothesis test.

9. ) Having two types of cars called type A and type B. In observing the miles per gallon we found that both types make mean miles per gallon of 32. Car A has a standard deviation of 5 miles per gallon while car B has a standard deviation of 3 miles per gallon. Which of the two car types is more consistent in fuel consumption?

10. A researcher is interested in studying people’s mean age in a certain region. If the population standard deviation is known to be 9 years and 2 year of error margin is allowed, find the minimum simple size the researcher needs to use, knowing that he is going to conduct his study using 90% confidence level
Submitted: 6 years ago.
Category: Math Homework
Expert:  Ryan replied 6 years ago.
Hi,

Welcome! Thank you for using JustAnswer. Here are the solutions:

Stats

Thanks,

Ryan
Customer: replied 6 years ago.
Thanks this is great I am going to expcept these answers. If I had about 3 or 4 more new questions can I add them here and edit the price or should I re ask them

thanks
Expert:  Ryan replied 6 years ago.
Hi,

Either way is fine.

If you put them in a new thread, you can add "For Ryan" to the beginning of the questions to be sure that they come to me.

Thanks,

Ryan
Customer: replied 6 years ago.
Ok I am going to place them here and edit the price.

1. The monthly utility bills are normally distributed with a mean value of \$130 and a standard deviation of \$15.
(a) Find the probability of having a utility bill between 100 and 150.
(b) Find the probability of having a utility bill less than \$90.
(c) Find the probability of having a utility bill more than \$160.

2. A Mall manager claims that in average every customer spends \$42 per a single visit to the mall. To test this claim, you took a sample of 49 customers and found the sample mean to be \$39 and the sample standard deviation to be \$9. At alpha = 0.05, test the Mall’s manager claim. Perform an appropriate hypothesis test, showing the necessary calculations and/or explaining the process used to obtain the results

3. A bank manager wanted to estimate the mean number of transactions businesses make per month. For a sample of 55 businesses, he found that mean number of transaction per month to be 32 and the standard deviation to be 7.5 transactions.
(a) Find a 90% confidence interval for the mean number of business transactions per month. Show your calculations and/or explain the process used to obtain the interval.
(b) Interpret this confidence interval and write a sentence that explains it.

4. A company’s CEO wanted to estimate the percentage of defective product per shipment. In a sample containing 400 products, he found 25 defective products.

(a) Find a 95% confidence interval for the true proportion of defective product. Show your calculations and/or explain the process used to obtain the interval.
(b) Interpret this confidence interval and write a sentence that explains it.

Expert:  Ryan replied 6 years ago.
Hi,

Sorry for the delay. I was tied up with another project.

I'm working on the new problems now and will have the solutions posted shortly.

Thanks,

Ryan
Customer: replied 6 years ago.
Thanks
Also for number 2 on the first set the "At the drive in question?" Would you say that is a binomial, poisson probablility experiment or neither.

Thanks
Expert:  Ryan replied 6 years ago.
Hi,

#2 from the first set is a Poisson distribution problem.

Here are the solutions for the second set of problems:

Stats2