The binomial probability distribution is a family of probability distributions with every single distribution depending on the values of n and p. Assume that x is a binomial random variable with n = 4.

  1. Determine a value of p such that the probability distribution of x is symmetric.
  2. Determine a value of p such that the probability distribution of x is skewed to the right.
  3. Determine a value of p such that the probability distribution of x is skewed to the left.
  4. Graph each of the binomial distributions you obtained in parts a, b, and c. Locate the mean for each distribution on its graph.\
  5. In general, for what values of p will a binomial distribution be symmetric? Skewed to the right? Skewed to the left?

Short Answer

Expert verified
  1. The probability distribution of x is symmetric if p=0.5.
  2. The probability distribution of x is skewed to the right if 0.5<p<1.
  3. The probability distribution of x is skewed to the left if 0<p<0.5.

e. A binomialdistribution will be symmetric if=0.5, postivelyskewedif 0.5<p<1, and negatively skewedif0<p<0.5.

Step by step solution

01

Definition of a symmetric binomial probability distribution 

a.

In a symmetric binomial probability distribution, the probability of successes will be equal to that of the failures. In the case of tossing a coin, the probabilitiesof heads and tails are equal, and this can be an example of a symmetric binomial probability distribution

02

Determination of the value 

From the definition, as it can be envisaged,the probability will be the same for both variables, and the calculation is shown below:

Probability=Totalprobability2=12=0.5

From the above calculation, it can be envisaged that the probability is 0.5.

03

Determination of the skewness 

b. Skewness, in terms of a binomial probability distribution, determines which side of the curve has deviated from the normal distribution. Whenever the skewness remains onthe right, it indicates that the skewness is positive, and when the skewness is toward the left, it indicates that the skewness is negative.

04

Determination of the valueof x 

Whenever the skewness remains positive (to the right), it means that the value of p must be more than 0.5. As the maximum probability can be upto 1, the value will stay between 0.5 and 1.

05

Determination of the value of p 

c. Whenever the skewness remains negative (to the left), it means that the value of p must be less than 0.5.As the minimum probability can be 0, the value will stay between 0 and 0.5

06

Elucidation of the graphs obtained in Parta

d. On the horizontal axis, the probabilities are plotted, and on the horizontal axis, the values are plotted from 1 to 5.In this case, it is symmetric.So, the mean value, 3,shows the highest probability

07

Elucidation of the graphsobtained in Part b

On the horizontal axis, the probabilities are plotted, and on the horizontal axis, the values are plotted from 1 to 8. In this case, it is positively skewed.So, the mean value, 4,doesnot show the highest probability, but instead, 3 showsthe highest probability.

08

Elucidation of the graphs obtained in Part c

On the horizontal axis, the probabilities are plotted, and on the horizontal axis, the values are plotted from 1 to 8.In this case, it is negatively skewed.So, the mean value, 4,doesnot show the highest probability, but instead, 6 showsthe highest probability.

09

Elucidation of p when the distribution is symmetric

Here, the value of p remains 0.5, and it indicates that the mean value of x shows the highest probability.In this case, the left tail remains exactly equal to the right tail when plotted on the graph.

10

Elucidation of p when the distribution is positively skewed

Here, the value of p remains above 0.5, and it indicates that the mean value of x does not show the highest probability.In this case, the right tail remains greater than the left tail when plotted on the graph.

11

Elucidation of p when the distribution is negatively skewed

Here, the value of p remains below 0.5, and it indicates that the mean value of x does not show the highest probability.In this case, the left tail remains greater than the right tail when plotted on the graph.

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Most popular questions from this chapter

Estimating demand for white bread. A bakery has determined that the number of loaves of its white bread demanded daily has a normal distribution with mean 7,200 loaves and standard deviation 300 loaves. Based on cost considerations, the company has decided that its best strategy is to produce a sufficient number of loaves so that it will fully supply demand on 94% of all days.

a. How many loaves of bread should the company produce?

b. Based on the production in part a, on what percentage of days will the company be left with more than 500 loaves of unsold bread?

Choosing portable grill displays. Refer to the Journal of Consumer Research (Mar. 2003) marketing study of influencing consumer choices by offering undesirable alternatives, Exercise 3.109 (p. 204). Recall that each of 124 college students selected showroom displays for portable grills. Five different displays (representing five different-sized grills) were available. Still, the students were instructed to select only three displays to maximize purchases of Grill #2 (a smaller-sized grill). The table shows the grill display combinations and the number of times each was selected by the 124 students. Suppose one of the 124 students is selected at random. Let x represent the sum of the grill numbers selected by this student. (This value indicates the size of the grills selected.)

a. Find the probability distribution for x.

b. What is the probability that x exceeds 10?

Flaws in the plastic-coated wire. The British Columbia Institute of Technology provides on its Web site (www.math.bcit.ca) practical applications of statistics at mechanical engineering firms. The following is a Poisson application. A roll of plastic-coated wire has an average of .8 flaws per 4-meter length of wire. Suppose a quality-control engineer will sample a 4-meter length of wire from a roll of wire 220 meters in length. If no flaws are found in the sample, the engineer will accept the entire roll of wire. What is the probability that the roll will be rejected? What assumption did you make to find this probability?

Stock market participation and IQ. Refer to The Journal of Finance (December 2011) study of whether the decision to invest in the stock market is dependent on IQ, Exercise 3.46 (p. 182). Recall that an IQ score (from a low score of 1 to a high score of 9) was determined for each in a sample of 158,044 Finnish citizens. Also recorded was whether or not the citizen invested in the stock market. The accompanying table gives the number of Finnish citizens in each IQ score/investment category. Which group of Finnish citizens (market investors or noninvestors) has the highest average IQ score?

IQ Score

Invest in market

No investment

Totals

1

893

4659

5552

2

1340

9409

10749

3

2009

9993

12002

4

5358

19682

25040

5

8484

24640

33124

6

10270

21673

31943

7

6698

11260

17958

8

5135

7010

12145

9

4464

5067

9531

Totals

44651

113393

158044

Consider the probability distribution shown here

  1. Calculate μ,σ2andσ.
  2. Graph p(x). Locateμ,μ2σandμ+2σ on the graph.
  3. What is the probability that x is in the interval μ+2σ ?
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