Answer:
The minimum sample needed to provide a margin of error of 3 or less is 52.
Step-by-step explanation:
The confidence interval for population mean (<em>μ</em>) is:

The margin of error is:

<u>Given:</u>
MOE = 3
<em>σ </em>= 11
The critical value for 95% confidence interval is: 
**Use the <em>z</em>-table for critical values.
Compute the sample size (<em>n</em>) as follows:

Thus, the minimum sample needed to provide a margin of error of 3 or less is 52.
Step-by-step explanation:
In order to find the better buy, we must find the cheaper unit price or price per gallon. To find the price per gallon, divide the cost by the number of gallons.
Mary
Mary bought 4 gallons for $11.
The price is $11 and the gallons are 4.
Jill
Jill bought 2.5 gallons for $7.25
The price is $7.25 and the gallons are 2.5
Better buy
Mary paid $2.75 per gallon and Jill paid $2.90 per gallon. 2.75 is less than 2.90, so Mary had the better buy.
Answer:
B. $3.45
Step-by-step explanation:
Number of cases of soda bought = 12
Total bill payed = $41.40
Let x represent the cost of 1 case.
Thus:
12x = $41.40
Divide both sides by 12
12x/12 = 41.40/12
x = 3.45
Cost of each case = x = $3.45
70+95=165
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