PLEASE NEED HELP

(1) What is the smallest sample size that guarantees that the margin of error is less than 41 when constructing a 93% confidence interval for a population mean with the assumed population standard deviation of 811.57?

(Round UP to the nearest integer)

(2) An incubation period is a time between when you contract a virus and when your symptoms start. By surveying randomly selected local hospitals, a researcher was able to obtain a sample of incubation periods of 20 patients, and the sample average was found to be 6.16 days. Assume that the population standard deviation is 1.7 days. Construct a 95% confidence interval for the average incubation period of the novel coronavirus. You may also assume that the sample is from a normal population.

1. Procedure: Select an answer One variance procedure One mean Z procedure One proportion Z procedure One mean T procedure Correct
2. Assumptions: (select everything that applies)
3. Unknown parameter: Select an answer , population variance p, population proportion , population mean Correct

Part 2 of 5

1. Point estimate: Select an answer sample variance, s sample proportion, p sample mean, x Correct =Correctdays (Round the answer to 2 decimal places)
2. Confidence level Correct% and = Correct, also
   • 2= Correct, and 1-2= Correct
   • Critical values: (Round the answer to 2 decimal places)
     • left=Correct right=Correct

Part 3 of 5

1. Margin of error (if applicable): (Round the answer to 2 decimal places)
2. Lower bound: (Round the answer to 2 decimal places)
3. Upper bound: (Round the answer to 2 decimal places)

• Population standard deviation is unknown
• Population standard deviation is known
• Normal population
• The number of positive and negative responses are both greater than 10
• Simple random sample
• Sample size is greater than 30

1. Correct

(3)

A local auto mechanic wanted to study the average time between oil changes and collected a simple random sample of 49 customers. The average time between the oil changes in the sample is 135.04 days. Construct and interpret a 97% confidence interval for the the average number of days between oil changes. Assume that the population standard deviation is 21.7 days.

1. Procedure: Select an answer One variance procedure One proportion Z procedure One mean Z procedure One mean T procedure Correct
2. Assumptions: (select everything that applies)
3. Unknown parameter: Select an answer , population variance , population mean p, population proportion Correct

Part 2 of 5

1. Point estimate: Select an answer sample mean, x sample variance, s sample proportion, p =days (Round the answer to 2 decimal places)
2. Confidence level % and= , also
   • 2= , and1-2=
   • Critical values: (Round the answer to 2 decimal places)
     • left= right=

• The number of positive and negative responses are both greater than 10
• Sample size is greater than 30
• Simple random sample
• Population standard deviation is unknown
• Population standard deviation is known
• Normal population

1. Correct

(4)

The Specific Absorption Rate (SAR) for a cell phone measures the amount of radio frequency (RF) energy absorbed by the user's body when using the handset. Every cell phone emits RF energy. Different phone models have different SAR measures. To receive certification from the Federal Communications Commission (FCC) for sale in the United States, the SAR level for a cell phone must be no more than 1.6 watts per kilogram. A sample of 17 models was tested and the average of their Specific Absorption Rates (SARs) was found to be 1.09 watts per kilogram. Assume that the population standard deviation is 0.25 watts per kilogram.Construct a 98% confidence interval for the mean of the SARs for cell phones that received certification from FCC. You may also assume that the sample is from a normal population.

1. Procedure: Select an answer One mean T procedure One variance procedure One proportion Z procedure One mean Z procedure Correct

Hint:In the question, look for the keywords such as mean/average, proportion/percentage, variance/standard deviation!

1. Assumptions: (select everything that applies)
2. Unknown parameter: Select an answer , population mean , population variance p, population proportion Correct

Part 2 of 5

1. Point estimate: Select an answer sample proportion, p sample variance, s sample mean, x =watts per kilogram (Round the answer to 2 decimal places)
2. Confidence level % and= , also
   • 2= , and1-2=
   • Critical values: (Round the answer to 2 decimal places)
     • left= right=

• The number of positive and negative responses are both greater than 10
• Simple random sample
• Population standard deviation is unknown
• Normal population
• Population standard deviation is known
• Sample size is greater than 30

1. Simple random sample Normal population Population standard deviation is knownPartially correct

(5) One of the characteristics of a credit card is the average outstanding balance. A group of researchers wants to estimate the average outstanding balance using a randomly selected sample of 16 customers. The average monthly balance of the sample is calculated as $2270.99. Construct and interpret a 94% confidence interval for the average outstanding balance on a credit card assuming that the population standard deviation is $2903.1. You may also assume that the sample is from a normal population.

1. Procedure: Select an answer One mean Z procedure One mean T procedure One variance procedure One proportion Z procedure Correct

Hint: In the question, look for the keywords such as mean/average, proportion/percentage, variance/standard deviation!

1. Assumptions: (select everything that applies)
2. Unknown parameter: Select an answer p, population proportion , population mean , population variance Correct

Part 2 of 5

1. Point estimate: Select an answer sample proportion, p sample variance, s sample mean, x Correct =Correctdollars (Round the answer to 2 decimal places)
2. Confidence level Correct% and = Correct, also
   • 2= Correct, and 1-2= Correct
   • Critical values: (Round the answer to 2 decimal places)
     • left=Correct right=Correct

Part 3 of 5

1. Margin of error (if applicable): (Round the answer to 2 decimal places)
2. Lower bound: (Round the answer to 2 decimal places)
3. Upper bound: (Round the answer to 2 decimal places)

• The number of positive and negative responses are both greater than 10
• Sample size is greater than 30
• Simple random sample
• Population standard deviation is unknown
• Normal population
• Population standard deviation is known

1. Correct