Test whether these data might come from a population with a mean Sales value of 9.5. – What is the p-value?

Midterm 1: Coke vs. Pepsi
• In a random sample of 20 potential customers,
what is the smallest number that must prefer
Coke to Pepsi for us to conclude with 80%
confidence that at least 75% of the population
of potential customers prefers Coke to Pepsi?
– Please give your answer as an integer, like 12.
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Midterm 2: Coke vs. Pepsi (Cont.)

• In a sequential random sample of potential
customers, what is the smallest possible
sample size number that must be sampled to
conclude with 80% confidence that at least
75% of the population of potential customers
prefers Coke to Pepsi, if all sampled people
respond that they prefer Coke to Pepsi?
– Please give your answer as an integer, like 12.
51
Midterm 3: Coke vs. Pepsi (Cont.)
• In a taste test conducted with a random
sample of 20 potential customers, what is the
smallest number that must prefer Coke to
Pepsi for us to conclude with 98% confidence
that more than 2/3 of the population of
potential customers prefers Coke to Pepsi?
– Please give your answer as an integer, like 12.
52

Midterm 4: Mean Sales
• Data on car seat sales at the first 30 stores in the
Carseats dataset are as follows: head(Sales, 30) =
c(9.50, 11.22, 10.06, 7.40, 4.15, 10.81, 6.63,
11.85, 6.54, 4.69, 9.01, 11.96, 3.98, 10.96, 11.17,
8.71, 7.58, 12.29, 13.91, 8.73, 6.41, 12.13, 5.08,
5.87, 10.14, 14.90, 8.33, 5.27, 2.99, 7.81)
• Test whether these data might come from a
population with a mean Sales value of 9.5.
– What is the p-value?
– Please round to 3 digits, like 0.123
53
Midterm 5: Mango weights
• A simple random sample of 30 mangos from a
large shipment had the following weights: x <-
c(1.41, 1.78, 3.18, 1.94, 8.43, 1.12, 3.00, 7.28,
1.35, 4.03, 1.67, 1.37, 6.50, 9.25, 2.54, 5.22, 1.27,
2.60, 1.98, 7.57, 3.05, 7.49, 7.53, 7.20, 2.98, 6.52,
4.78, 5.84, 1.00, 3.26)
• Test whether these data might come from a
population with a median value of 6.
– What is the p-value?
– Please round your answer to 3 digits, like 0.123
54
Midterm 6: Mango weight upper
confidence limit
• A simple random sample of 30 mangos from a
large shipment had the following weights: x <-
c(1.41, 1.78, 3.18, 1.94, 8.43, 1.12, 3.00, 7.28,
1.35, 4.03, 1.67, 1.37, 6.50, 9.25, 2.54, 5.22, 1.27,
2.60, 1.98, 7.57, 3.05, 7.49, 7.53, 7.20, 2.98, 6.52,
4.78, 5.84, 1.00, 3.26)
• What is an estimated upper 80% confidence limit
for the population median, based on these data?
– Please round your answer to 2 digits, like 1.23
55
Midterm 7: Campaign effects
• Data on monthly car seat sales at 30 stores in Colorado are
as follows: x = c(9.50, 11.22, 10.06, 7.40, 4.15, 10.81, 6.63,
11.85, 6.54, 4.69, 9.01, 11.96, 3.98, 10.96, 11.17, 8.71, 7.58,
12.29, 13.91, 8.73, 6.41, 12.13, 5.08, 5.87, 10.14, 14.90,
8.33, 5.27, 2.99, 7.81)
• Following a new marketing campaign, the monthly car seat
sales at the same 30 stores were as follows: y = c(11.12,
11.50, 10.68, 8.43, 4.21, 9.91, 7.10, 12.73, 6.78, 5.39, 10.30,
12.51, 3.79, 11.19, 11.28, 8.63, 7.90, 12.25, 14.53, 9.89,
6.36, 11.84, 5.28, 6.04, 10.24, 15.30, 9.20, 5.29, 3.56, 9.02)
• Find a two-sided 95% lower confidence limit (LCL) for the
change in mean sales per month per store from before the
new campaign to after it. What is the 95% LCL for the mean
increase in Sales per store?
– Please round to 3 digits, like 0.123
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