# Statistics : 25 questions | Mathematics homework help

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**QUESTIONS :**

**Question 1 of 25**1.0 Points

Which of the following statistics is not a measure of central location?

A.Mode

B.Mean

C.Median

D.Interquartile range

**Question 2 of 25**1.0 Points

If A and B are any two events with P(A) = .8 and then is:

A.0.875

B.0.14

C..24

D.0.56

**Question 3 of 25**1.0 Points

If one tosses a coin enough times, the proportion of “heads” will approach 0.5. This is an example of:

A.the Law of Large Numbers

B.subjective probabilities

C.the Central Limit Theorem

D.the Empirical Rule

**Question 4 of 25**1.0 Points

A discrete probability distribution:

A.can be estimated from long-run proportions

B.is a tool that can be used to incorporate uncertainty into models

C.is the distribution of multiple random variables

D.lists all of the possible values of the random variable and their corresponding probabilities

**Question 5 of 25**1.0 Points

A drug is reported to benefit 40% of the patients who take it. If 6 patients take the drug, what is the probability that 4 or more patients will benefit?

A.0.138

B.0.862

C.0.667

D.0.179

**Question 6 of 25**1.0 Points

Find the variance of the following probability distribution.

XP(X)

10.20

20.35

30.10

40.25

50.10

A.1.83

B.1.31

C.1.25

D.1.71

**Question 7 of 25**1.0 Points

Find the probability, P(Z < 0.17), using the standard normal distribution.

A..8300

B..4325

C..5675

D..0675

**Question 8 of 25**1.0 Points

The continuous distribution characterized by a symmetric, bell-shaped curve is the:

A.normal distribution

B.binomial distribution

C.exponential distribution

D.Poisson distribution

**Question 9 of 25**1.0 Points

Given that Z is a standard normal random variable, P(-1.0 < Z < 1.5) is

A.0.9332

B.0.7745

C.0.8413

D.0.0919

**Question 10 of 25**1.0 Points

The standard normal distribution has a mean of ___ and standard deviation of ___, respectively.

A.0 and 0

B.1 and 0

C.1 and 1

D.0 and 1

**Question 11 of 25**1.0 Points

One reason for standardizing random variables is to measure variables with:

A.dissimilar means and similar standard deviations in like terms

B.similar means and standard deviations on two scales

C.different means and standard deviations on a single scale

D.different means and standard deviations on a non-standard scale

**Question 12 of 25**1.0 Points

The mean of a probability distribution is a:

A.measure of relative likelihood

B.measure of central location

C.measure of variability of the distribution

D.measure of skewness of the distribution

**Question 13 of 25**1.0 Points

The histogram below represents scores achieved by 250 job applicants on a personality profile.

What percentage of the job applicants scored below 60? Place your answer in the blank, rounded to 2 decimal places. Do not use a percentage sign (%). For example, 44.44 would be a legitimate answer.

**Question 14 of 25**1.0 Points

Find the expected value of the following probability distribution.

X12345

P(X)0.050.200.350.250.15

Round your answer to two decimal place as necessary. For example, 4.56 would be a legitimate entry.

Expected value =

**Question 15 of 25**1.0 Points

The following data were obtained from a survey of college students. The variable *X* represents the number of non-assigned books read during the past six months.

*x*0123456

*P* (*X*=*x*)0.550.150.100.100.040.030.03

Find P(X > 0). Place your answer, rounded to two decimal places in the blank. For example, 0.56 would be a legitimate entry.

**Question 16 of 25**1.0 Points

Mothers Against Drunk Driving (MADD) is a very visible group whose main focus is to educate the public about the harm caused by drunk drivers. A study was recently done that emphasized the problem we all face with drinking and driving. Five hundred accidents that occurred on a Saturday night were analyzed. Two items noted were the number of vehicles involved and whether alcohol played a role in the accident. The numbers are shown below:

* Number of Vehicles Involved*

*Did alcohol play a role?*123

Yes6011030200

No4021545300

10032575

What proportion of accidents involved alcohol and a single vehicle?

Place your answer, rounded to 2 decimal places, in the blank. For example, 0.23 is a legitimate entry.

**Question 17 of 25**1.0 Points

An ice cream vendor sells three flavors: chocolate, strawberry, and vanilla. Forty five percent of the sales are chocolate, while 30% are strawberry, with the rest vanilla flavored. Sales are by the cone or the cup. The percentages of cones sales for chocolate, strawberry, and vanilla, are 75%, 60%, and 40%, respectively. For a randomly selected sale, define the following events:

= chocolate chosen

= strawberry chosen

= vanilla chosen

= ice cream on a cone

ice cream in a cup

Find the probability that the ice cream was vanilla flavor, given that it was sold in a cup. Place your answer, rounded to 4 decimal places, in the blank. For exampe, 0.3456 would be a legitimate entry.

**Question 18 of 25**1.0 Points

Suppose that the average weekly earnings for employees in general automotive repair shops is $450, and that the standard deviation for the weekly earnings for such employees is $50. A sample of 100 such employees is selected at random.

Find probability that the mean of the sample is less than $445. Place your answer, rounded to 4 decimal places, in the blank. For example, 0.2345 would be a legitimate entry.

**Question 19 of 25**1.0 Points

Scores on a mathematics examination appear to follow a normal distribution with mean of 65 and standard deviation of 15. The instructor wishes to give a grade of “C” to students scoring between the 60th and 70th percentiles on the exam.

What score represents the 60th percentile score on the mathematics exam? Place your answer in the blank, rounded to a whole number. For example, 62 would be a legitimate entry.

**Question 20 of 25**1.0 Points

Suppose that the average weekly earnings for employees in general automotive repair shops is $450, and that the standard deviation for the weekly earnings for such employees is $50. A sample of 100 such employees is selected at random.

Find the mean of the sampling distribution of the means of average weekly earnings for samples of size 100. Place your answer in the blank. Do not include a dollar sign. For example, 123 would be a legitimate entry.

**Question 21 of 25**1.0 Points

A Wendy’s fast-food restaurant sells hamburgers and chicken sandwiches. On a typical weekday, the demand for hamburgers is normally distributed with a mean of 450 and standard deviation of 80 and the demand for chicken sandwiches is normally distributed with a mean of 120 and standard deviation of 30.

How many chicken sandwiches must the restaurant stock to be 99% sure of not running out on a given day? Place you answer, rounded to the nearest whole number in the blank. For example, 345 would be a legitimate entry.

**Question 22 of 25**1.0 Points

Suppose that the average weekly earnings for employees in general automotive repair shops is $450, and that the standard deviation for the weekly earnings for such employees is $50. A sample of 100 such employees is selected at random.

Find the probability that the mean of the sample is greater than $460. Place your answer, rounded to 4 decimal places, in the blank. For example, 0.2345 would be a legitimate answer.

**Question 23 of 25**1.0 Points

Mrs. Smith’s reading class can read a mean of 175 words per minute with a standard deviation of 20 words per minute. The top 3% of the class is to receive a special award. Assuming that the distribution of words read per minute are normally distributed, what is the minimum number of words per minute a student would have to read in order to get the award? Place your answer, **rounded to the nearest whole number**, in the blank. When entering your answer do not use any labels or symbols. Simply provide the numerical value. For example, 123 would be a legitimate entry.

**Question 24 of 25**1.0 Points

Using the standard normal curve, the Z- score representing the 99th percentile is 2.326.

True

False

**Question 25 of 25**1.0 Points

The left half under the normal curve is slightly smaller than the right half.

True

False