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**True or false statistics**

- From Mathematics, Statistics

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Question 1

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"Tom's SUV rolled over. Therefore, SUVs are dangerous." Which of the following fallacy does this statement best illustrate?

Select one:

a. Confusing significance with importance.

b. Interpreting a correlation as a causal link.

c. Making conclusions about the population from a small sample.

d. Generalizing from an average to an individual.

Question 2

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True or False? A population can be divided into several groups, where the within group variations are small but the cross group variations are large. The proper sampling method applied to this population is __convenience sampling__.

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True

False

Question 3

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If you have 33 data observations in a sample, how many classes (bins) does the Sturges' Rule recommend for you to construct a frequency distribution table?

Select one:

a. 8

b. 9

c. 6

d. 4

Question 4

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True or False? It is __inappropriate__ to apply the Chebyshev's theorem to a population that is left-skewed.

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True

False

Question 5

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True or False? When two events are mutually exclusive and collectively exhaustive, then it must be the case that one event is __the complement of the other__.

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True

False

Question 6

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Use the contingency table below to calculate .

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a. 0.2500

b. 0.6250

c. 0.7500

d. 0.1250

Question 7

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True or False? There is a 30% chance that a car’s service time is considered “late” in a quick oil change shop in Boone. Suppose this shop services in total 5 cars today. Define a new random variable X the number of cars with “late” service today. Then the probability that none of the 5 cars are serviced “late” P(X=0) is __0.168__.

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True

False

Question 8

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When you send out a resume, the probability of being called for an interview is 0.20. What is the probability that the first interview occurs on the fourth resume that you send out?

Select one:

a. 0.4096

b. 0.0016

c. 0.2410

d. 0.1024

Question 9

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The time required for a citizen to complete a 2000 U.S. Census “long” form is normally distributed with a mean of 40 minutes and a standard deviation of 10 minutes. Use the C-2 table below to find the probability that a randomly selected citizen will need less than 58 minutes to complete a “long” form.

Select one:

a. 0.9641

b. 0.9656

c. 0.9772

d. 0.9713

Question 10

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A company has 300 employees. Each year, there is a 30% turnover rate for the employees. The total number of employees who leave each year follows a binomial distribution. Now, we want to use the normal approximation to this binomial distribution. Then in this normal distribution, the mean is ______ and the standard deviation is _____.

Select one:aqq

a. 90, 63

b. 90, 7.937

c. 63, 30

d. 30, 15

Question 11

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Between 2 and 4 PM on Wednesday, patient insurance inquiries arrive at Blue Choice insurance with a mean rate of 2.6 calls per minute. What is the probability of waiting more than 1.5 minutes to get the next inquiry call?

Select one:

a. 0.2564

b. 0.0122

c. 0.0535

d. 0.0202

Question 12

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A consistent estimator (such as the sample mean) for the population mean

Select one:

a. converges to the population mean as the sample size increases.

b. converges to the population mean as the sample variance increases.

c. consistently follows a continuous uniform distribution.

d. is impossible to calculate using any random sample.

Question 13

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True or False? The Central Limit Theorem suggests that, if the sample size n is greater than 60, then it must be the case __that the population will follow a normal distribution__.

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True

False

Question 14

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True or False? A 90% confidence interval for the population mean will be __shorter__ than a 95% confidence interval for the population mean, for a given random sample.

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True

False

Question 15

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True or False? The Student’s *t* distribution approaches the standard normal distribution *z* __as the degrees of freedom go up.__

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True

False

Question 16

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In a random sample of 16 ATM transactions at a bank, the sample mean transaction time is 2 minutes with the sample standard deviation of 1.6 minutes. We can use this sample to construct a 95% confidence interval (in minutes) for the population mean transaction as_______, after applying the table below to get the Student’s t statistic.

Select one:

a. (1.2988, 2.7012)

b. (1.1520, 2.8480)

c. (1.1476, 2.8524)

d. (1.4652, 2.5348)

Question 17

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True or False? When n = 30 and p (p is the sample proportion) = 0.4, the sample proportion can be safely assumed to follow __a normal distribution.__

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True

False

Question 18

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If the population standard deviation *σ* = 25, what is the required minimum sample size to construct a 90% confidence level for the population mean with an allowable error of ± 3, using Z0.05=1.645?

Select one:

a. 426

b. 512

c. 267

d. 188

Question 19

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True or False? A 25-year-old man in Boone complains of chest pain. He wants to be admitted by a hospital as a patient because he believes he has a heart attack. Heart attacks in 25 year olds are rare, and medical treatments on heart attacks are expensive in the hospital. The null hypothesis is that the man has no heart attack. For a given test on whether the man has a heart attack, the probability of committing a Type II error is: __P(The hospital does not admit him as a heart attack patient | The man has a heart attack).__

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True

False

Question 20

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True or False? For a given sample size and a given test on a pair of hypotheses, reducing the probability of committing a Type II error __increases__ the power of the test.

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True

False

Question 21

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True or False? In testing the hypotheses *H*0: µ ≤30, *H*1: µ >30 where 30 is the hypothesized mean of a population, we must use __a left-tailed test. __

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True

False

Question 22

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When testing the hypothesis *H*0: μ = 100, *H*1: μ ≠100, with known population variance *σ*^{2 }= 100, we find that the sample mean is 103 in a random sample of 100 items. The test statistic is

Select one:

a. 1.645

b. 1.960

c. 0.300

d. 3.000

Question 23

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In a right-tailed hypothesis test on a population mean (suppose the population standard deviation is known), the test statistic z = 1.68. The p-value is (Use the partial C-2 table below):

Select one:

a. 0.0465

b. 0.9535

c. 0.1186

d. 0.0179

Question 24

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True or False? In a sample of 16 items, the sample mean is 63 and the sample standard deviation is 10. The critical values of the Student’s t statistics (with the degrees of freedom 15) are ±1.753 for a two tailed test, at . Then, we __should reject__ H0 (when ):

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True

False

Question 25

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True or False? A company tracks a shopper’s record of bringing back items. The historical return rate for merchandise at department stores is 13.0 percent. At one department store, after installing a new software to crack down on “serial exchangers”, there are 15 returns in a sample of 250 purchases. At* *, we __should reject the null hypothesis__ that the true return rate in this store after the software was installed is at least 0.13 (You will use one of the following Z values: 2.326 for a right-tailed test, ±2.576 for a two-tailed test , -2.326 for a left-tailed test).

Select one:

True

False

**True or false statistics**

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- Submitted On 13 Jun, 2017 10:59:50

**Mickeygabz****Rating :**1**Grade :****A+****Questions :**1**Solutions :**100**Blog :**0**Earned :**$101.75