The Average Lifetime of 25 Randomly Selected Certain Brand Tvs Is 15 Years. Suppose The

Name:

Section:

HWK 6.1 and 6.2

PROBLEM 1

The average lifetime of 25 randomly selected certain brand TVs is 15 years. Suppose the SD of all TVs is 3 years.

Construct a 90% CI for the average lifetime of all TVs from this brand. (2 DECIMAL PLACES)

(1) Lower Bound = ______

(2) Upper Bound = ______

Problem 2:

The average height of 81 randomly selected UNCW students is 5.5 feet. Suppose the SD of the heights of all students is .75 feet.

Construct 99% CI for the average height of all students. (2 Decimals)

(3) Lower: ______

(4) Upper: ______

Range = Upper – Lower = ______

Construct 95% and CI for the average height of all students. (2 Decimals)

(5) Lower: ______

(6) Upper: ______

Range = (upper – lower) =

Construct 90% CI for the average height of all students.(2 Decimals)

(7) Lower: ______

(8) Upper: ______

Range = (upper – lower) =

(9) Which level of confidence has the largest interval?

90 or 95 or 99 ?

Redo the 95% Confidence Interval with n = 225 (2 Decimals)

(10) Lower: ______

(11) Upper: ______

Range = (upper – lower) =

(12) For what value of n is the 95% Confidence Interval smaller?

81 or 225

Problem 3:

In a clinical study with 121 cancer patients, a new medicine can on average prolong 3 years of life. Suppose the Standard Deviation of all cancer patients is 1.8

Construct a 90% CI for the average life the medicine can prolong for all cancer patients.

(13) Lower: ______(2 Decimals)

(14) Upper: ______(2 Decimals)

Problem 4:

Because of variation in the manufacturing process, tennis balls produced by a particular machine do not have identical diameters, which is supposed to be 3in. The population SD is 0.15 in. If the average diameters of the first 36 balls made from a machine is 3.2in,shall we stop and calibrate the machine? USE α = .05 for your level of significance

Ho: ______

Ha: ______

Alpha: .05 (LEVEL OF SIGNIFICANCE)

(15) Z= ______

(16) P-Value = ______

(17) Reject the Ho or Fail to Reject the Ho?

Problem 5

The National Center for Health Statistics reports that the mean systolic blood pressure for males 35 to 44 years of age is 136 with a population SD=18.

The medical director of a company looks at the medical records of 92 company executives in this age group and finds that the mean systolic blood pressure in this sample is 134. Is this evidence that executives blood pressures are lower than the national average?

H0: ______

Ha: ______

Alpha: .05 (LEVEL OF SIGNIFICANCE)

(18) Z = ______(2 Decimals)

(19) P-Value ______(4 Decimals)

(20) Reject the Ho or Fail to Reject the Ho?

Problem 6

In a discussion of SAT Mathematics(SATM)scores,someone comments:“Because only a select minority of California high school students take the test,the scores overestimate the ability of typical high school seniors.I think that if all seniors took the test,the mean score would be no more than 475.” You do not agree with this claim and decide to use a SRS of 500 seniors to assess the degree of evidence against it.Those 500 seniors had a mean SATM score of= 485.Is this strong enough evidence to conclude that this person’s claim is wrong? Use standard deviation = 100 and alpha = .05

Ho:

Ha:

n = 500, xbar = 485

(21) z = ______(2 Decimals)

(22) p-value = ______(4 Decimals)

(23) Reject the Ho or Fail to Reject the Ho?

What if level of significance was .01 instead of .05?

(24) Reject the Ho or Fail to Reject the Ho?

Problem 7

Computing the test statistic andP-value.You will perform a significance test ofH0:μ= 26 based on an SRS ofn= 36.Assume thatσ= 7.

If= 27.5,what is the test statisticz

(25) z = ______(2 Decimals)

What is theP-value ifHa:μ> 26?

(26) Test Type: Left Tailed or Two Tailed or Right Tailed

(27) p = ______(4 Decimals)

What is theP-value ifHa:μ≠ 25?

(28)Test Type: Left Tailed or Two Tailed or Right Tailed

(29) p = ______(3 Decimals)

Problem 8

If No Significance Level is given, what should you use by default?

(30) alpha = ____

.01 or .001 or .05 or .005

Problem 9

A 95% confidence interval for a population mean is (18, 22).

(31) Can you reject the null hypothesis that H0 :µ = 19 at the 5% significance level? Yes or No

(32) Can you reject the null hypothesis that H0 :µ = 23 at the 5% significance level? Yes or No

Problem 10

The P-value for a two-sided test of the null hypothesis

mu = 30 is 0.07,

(33) Does the 99% confidence interval includes the value 30? Yes or No

(34) Does the 95% confidence interval includes the value 30? Yes or No

(35) Does the 90% confidence interval does not include the value 30? Yes or No