Open book Statistics Quiz

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Qrgrezvarq123

Mathematics

Bowie State University

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Please use the powerpoints I sent in the last assignments. Show all work and cold the answers please

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Name: 1. QUIZ 2 The lengths of time bank customers must wait for a teller are normally distributed, with a mean of 3 minutes and a standard deviation of 2 minute. a. What proportion of bank customers waits between 3 and 4 minutes b. What percentage wait more than 4 minutes? c. What proportion waits between 1 and 3 minutes? d. What percentage wait less than 1 minute? 2. To estimate the medical charges for an appendectomy Blue Star Insurance has data from a random sample of 75 patients. The sample mean cost is $400, with a sample standard deviation of $60. Construct a 95% confidence interval for the population mean cost. We are 95% confident that the populations mean costs of patients’ medical charges for an appendectomy through Blue Star Insurance range is between _____________ and ________________ 3. Democrat Republican Independent DC 10 15 65 Chicago 35 25 75 North Carolina 60 20 70 A group of voters from 3 states were selected and the results are above. What is the probability of selecting a random voter from Chicago, given that the voter was a republican? a).357 b).417 c).267 d).200 4.. Republican Democratic Independent Maryland 10 15 65 Los Angeles 35 25 75 Detroit 60 20 70 A group of voters from 3 areas were selected and the results are above. What is the probability of selecting a random voter that is from Detroit or a Republican? a).093 b).520 c).613 d).357 5. There is a bag with 62 tickets. 31 are blue and 31 are red. In 20 pulls from the bag, 20 tickets are red. What is the probability with replacement that the 21st pull will be red? a).5000 b).2500 c).000000477 d).03125 e) none of the above
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Explanation & Answer

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Name:

1.

QUIZ 2

The lengths of time bank customers must wait for a teller are normally distributed, with a mean of 3
minutes and a standard deviation of 2 minute.
a. What proportion of bank customers waits between 3 and 4 minutes
𝑃(3 ≤ 𝑥 ≤ 4) = 𝑃(𝑥 ≤ 4) − 𝑃(𝑥 ≤ 3)
4−3
3−3
𝑃(3 ≤ 𝑥 ≤ 4) = 𝑃 (𝑧 ≤
) − 𝑃 (𝑧 ≤
)
2
2
𝑃(3 ≤ 𝑥 ≤ 4) = 𝑃(𝑧 ≤ 0.5) − 𝑃(𝑧 ≤ 0)
𝑃(3 ≤ 𝑥 ≤ 4) = 0.6915 − 0.5
𝑃(3 ≤ 𝑥 ≤ 4) = 𝟎. 𝟏𝟗𝟏𝟓

b. What percentage wait more than 4 minutes?

𝑃(𝑥 ≥ 4) = 1 − 𝑃(𝑥 ≤ 4)
4−3
𝑃(𝑥 ≥ 4) = 1 − 𝑃 (𝑧 <
)
2
𝑃(𝑥 ≥ 4) = 1 − 𝑃(𝑧 < 0.5)
Using a z-score table we find the probabilities for z = 0.5
𝑃(𝑥 ≥ 4) = 1 − 0.6915
𝑃(𝑥 ≥ 4) = 0.3085
This is ...


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