QUESTION 1 The sales of a grocery store had an average of $9,000 per day. The st

Question

QUESTION 1 The sales of a grocery store had an average of $9,000 per day. The store introduced several At 95%confid nce, what is your cochano? O a The advertising campaigns have not been effective in increasing sales becase the sale is not signficantly greater than $9,000 O b The advertising campaigns have been effective O c. The advertising campaigns have been effective in increasing sales because the sale is significantly greater than $9,300 O d The advertising campaigns have mot been effective in increasing sales because the sale is not significantly greater than $9,300 in increasing sales, a sample of 64 days of sales was selected. it was found that the average was $9 advertising campaigns in order to sncrese sales To determine whether or not the advertising carspains huve been ,300 per day. From past infoemuation, it is known that the standad deviation of the pepuiation is $1,200 i increasing sales becase the sale is significantly greater than $9,000 QUESTION 2 The closer the sample mean is to the population mean o a the larger the sampling error is b.the sampling error equals l O c the smaller the sampling error is o d All of these alternatives are connect QUESTION 3 The sample size needed to provide a margin of enror of 3 or less with 95 probblity when the populaticn standard derviation equals 11 m O a 52 O b 51 Type here to 1/21/2017

Explanation / Answer

95% CONFIDENCE INTERVAL WITH KNOWN SD $1200

M = 9300
t = 1.96
sM = (12002/64) = 150

= M ± Z(sM)
= 9300 ± 1.96*150
= 9300 ± 293.99

M = 9300, 95% CI [9006.01, 9593.99].

You can be 95% confident that the population mean () falls between 9006.01 and 9593.99.

THE ADVERTISING CAMPAIGN HAVE BEEN EFFECTIVE IN INCREASING THE SALE BECAUSE SALE IS SIGNIFICANTLY GREATER THAN $9000

2) THE SMALLER THE SAMPLE ERROR SAMPLE MEAN CLOSER TO POPULATION MEAN.

3) MARGIN OF ERROR=3 CONFIDENCE LEVEL 0.95 AND S.D=11

EFFECT SAMPLE SIZE

=

Step 1: Find z a/2 by dividing the confidence interval by two, and looking that area up in the z-table:
.95/2 = 0.475. The closest z-score for 0.475 is 1.96.

Step 2: Multiply step 1 by the standard deviation.
1.96 * 11 = 21.56

Step 3: Divide Step 2 by the margin of error. Our margin of error (from the question), is 3.
21.56/3 = 7.19

Step 4: Square Step 3.
7.19 * 7.19 = 51.69

EFFECT SAMPLE SIZE IS 52.

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