Final for decsion concpets

it is known that the variance of a population equals 1,936. a random sample of 121 has been taken from the population there is a .95 probability that the sample mean will provide a margin of error of

1,936

if there is a very strong correlation between two variables, then the coefficient of correlation must be

either much larger than 1 or much smaller than 1

if all the points of a scatter diagram lie on the least squares regression line, then the coeffcient of determination for these variables bases on these data

is 1

y = 50,000 +6x the above equation implies that an increase of

$1 in advertising is associated with an increase of 6,000 in sales

Construct a 95% confidence interval for the average sales in the grocery store after the advertising campaign

(8000.3,8599.7)

x independent variable 15 12 10 7 the least squares estimate of b1 equals

-0.7647

You are given the following information about y and x. y Dependent Variable x Independent Variable 5 1 4 2 3 3 2 4 1 5 69. Refer to Exhibit 14-2. The least squares estimate of b1 (slope) equals

-1

for a one-tailed test(lower tail) at 93.7% confidence Z =

-1.53

x indepeded variable 15 12 10 7 b0

-7.647

a sample of 20 cans of tomato juice showed a standard deviation of .4 ounce. a 95% confidence interval estimate of the variance for the population is

.0925 to .3413

if an interval estimate is said to be constructed at the 90% confidence level, the confidence coefficient would be

0.9

Read the z statistic from the normal distribution table and circle the correct answer. A one-tailed test (upper tail) at a 87.7% confidence; Z

1.16

for a two-tailed test, a sample of 20 at 80% confidence t =

1.328

for a one-tailed test(upper tail), a sample size of 18 at 95% confidence, t =

1.740

If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient is

1.96

n = 14 s = 20 H0: σ2 ≤ 500 Ha: σ2 ≥ 500

10.4

The sample size needed to provide a margin of error of 2 or less with a .95 probability when the population standard deviation equals 11 is

117

last year the standard deviation of the ages of the students at ua was 1.81 years. the test statistic is

12.1

the 95% confidence interval estimate for a population variance when a sample variance of 30 is obtained from a sample of 12 items is

15.05 to 86.48

From past information, it is known that the standard deviation of the sample is $1200. the value of the test statistic is

2.00

the critical value of t for a two tail test with 6 degrees of freedom and a alpha = 0.05 is

2.447

if we wanted to conduct a hypothesis test using a .05 level of signifance , what would be our critical value ?

2.57

a Machine that produces a major part for an airplane engine is monitored closely. in the past, 10% of the parts produced would be defective. with a .95 probability the sample size that needs to be taken if the desired margin of error is.04 or less is

217

n = 14 s = 20 H0: 2 410 Ha: 2 > 410 . The null hypothesis is to be tested at the 5% level of significance. The critical value(s) from the table is(are)

22.3621

the producer of a certain medicine claims that its bottling equipment is very accurate and that the standard deviation of all its filled bottles is 0.1 ounce or less. a sample of 20 bottles showed a standard deviation of .11 the test statistic to test the claim is

22.99

it is known that the population variance is 144 at 95 % confidence what size sample should be taken

23

From a population with a variance of 900, a sample of 225 items is selected. At 95% confidence, the margin of error is

3.92

the X2 value for a one-tailed(upper tail) hypothesis test of 95% confidence and a sample size of 25 is

36.4151

a random sample of 31 charge sales showed a a sample standard deviation of 50. a 90% confidence interval estimate of the population standard deviation is

39.96 to 66.83

the manager of the service department of a local car dealership has noted that the service times of a sample of a 30 new automobiles has a standard deviation of 6 minutes.

4.78 to 8.07

the 90% confidence interval estimate for a population standard deviation when a sample variance of 50 is obtained from a sample of 15 items is

5.44 to 10.32

x independent variable 1 2 3 4 5 the least squares estimate of b0(intercept) equals

6

What is the minimum size sample needed to estimate the population proportion with a margin of error not exceeding 4% at 95% confidence ? Hint:

600

a population has a standard deviation of 50. a random sample of 100 items from the population is selected the sample mean is determined to be 600. at 95% confidence, the margin of error is

609.8

it is known that the population variance equals 484. with a 0.95 probability, the sample size that needs to be taken if the desired margin of error is 5 or less is

75

one-tailed alternative hypotheses are phrased in terms of

< or >

which of the following statements are true of the null and alternative hypotheses ?

Exactly one hypothesis must be true

the average manufacturing work week in metropolitan Chattanooga was 40.1 hours

H0: u >=40.1 ha: oc < 40.1

in the simple linear regression, r2 is the

coefficient of determination

a measure of the strength of the relationship between two variables is the

correlation coeffcient

A regression analysis between demand ( y in 1000 units) and price ( x in dollars) resulted in the following equation = 9 - 3 x The above equation implies that if the price is increased by $1, the demand is expected to____________.

decrease by 3000 units

a test with 0.05 significance level has a larger rejection region than a test with .01 significance level

True

we are interested in testing to see if the variance of a population is less that 7. the correct null hypothesis s

a2 >= 49

Which sign is possible in an alternative hypothesis?

all these signs are possible

using an (x=0.04, a confidence interval for a population proportion is determined to be .65 to /75. if the level of significance is decreased, the interval for the population proportion

become wider

as the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution

becomes smaller

A sample of 28 elements is selected to estimate a95% confident interval for the variance ot the population. The chi-sqaure values to be used for this iterval estimationare?

c. 16.151 and 40.113

if the coefficient of determination is equal to 1, then the coefficient of correlation

can be any value between -1 and 1

the numerical value of the coefficient of determination

can be larger or smaller than the coefficient of correlation

larger values of r2 imply that the observations are more closely grouped about the

least squares line

it is possible for the coefficient of determination to be

less than 1

If a hypothesis is rejected at the 0.025 level of significance, it:

may or may not be rejected at the 0.01 level.

if the coefficient of correlation is a positive value, then the slope of the regression line

must also be positive

if the coefficient of correlation is a negative value, the the coefficient of determination

must be positive

A sample of n observations is taken from a population. when performing statistical inference about a population variance, the appropriate x2 distribution has

n - 1 degrees of freedom

Application of the least squares method results in values of the y intercept and the slope that minimizes the sum of the squared deviations between the

observed values of the dependent variable and the predicted values of the dependent variable

regression analysis is a statistical procedure for developing a mathematical equation that describes how

one dependent and one or more independent variables are related

if we wanted to conduct a hypothesis test using a .05 level of significance, which rejection rule would we use ?

reject H0 if |t| > ta/2

in regression analysis the variable that is being predicted is the

response variable/ dependent variable

last year the standard deviation of the ages of the students at ua was 1.81 years.At 95% confidence the null hypothesis

shoud not be rejected

n = 14 s = 20

should be reject

in determining the sample size necessary to estimate a population proportion, which of the following information is not needed ?

the mean of the population

n = 14 s = 20 H0: σ2 ≤ 500 Ha: σ2 ≥ 500

should not be rejected

the value set for alpha is known as the

significance level

in hypothesis testing if the null hypothesis is rejected,

the alternative hypothesis is true

a test with a 0.10 significance level has a larger rejection region than a test with a .05 significance level

true

the correct null hypothesis for this problem is ?

u<= 8000

the random variable for a chi-square distribution may assume any

value greater than 0

if we wanted to conduct a hypothesis test using a .05 level of significance, what would your conclusion be ?

we have enough evidence to reject the null hypothesis. so we can conclude that the advertising campaign did increase sales

In regression analysis, the independent variable is typically plotted on the _____.

x-axis of a scatter diagram