Compute the number of ways can select n element from N element of each of the following:

  1. n=2,N=5
  2. n=3,N=6
  3. n=5,N=20

Short Answer

Expert verified
  1. 10
  2. 20
  3. 15504

Step by step solution

01

Computing the number of ways to select 2 from 5

The value of C25 can be computed using the formula mentioned below:

Here, N=5 and n=2.

NN=N!n!N-n!52=5!2!5-2!=5×4×3×2×12×1×3×2×1=5×42×1=10

Therefore, the value of the number of ways to select2 from 5 using combination is 10.

02

Computing the number of ways to select 3 from 6

The value of C36 can be computed using the formula where N=6 andn=3 .

NN=N!n!N-n!63=6!3!6-3!=6×5×4×3×2×13×2×1×3×2×1=6×5×43×2×1=20

Therefore, the value ofC36=20.

03

Computing the number of ways to select 5 from 20

The value ofC520can be computed using the formula whereN=20andn=5.

NN=N!n!N-n!205=20!5!20-5!=20×19×18×17×16×15×14×13×12×11×10×9×8×7×6×5×4×3×2×15×4×3×2×1×15×14×13×12×11×10×9×8×7×6×5×4×3×2×1=20×19×18×17×165×4×3×2×1=15,504

Hence, the value ofC520=15504.

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Most popular questions from this chapter

Museum management. Refer to the Museum Management and Curatorship (June 2010) study of the criteria used to evaluate museum performance, Exercise 2.14 (p. 74). Recall that the managers of 30 leading museums of contemporary art were asked to provide the performance measure used most often. A summary of the results is reproduced in the table. Performance Measure Number of Museums Total visitors 8 Paying visitors 5 Big shows 6 Funds raised 7 Members 4


Performance Measure

Number of Museums

Total visitors

8

Paying visitors

5

Big shows

6

Funds raised

7

Members

4

a. If one of the 30 museums is selected at random, what is the probability that the museum uses total visitors or funds raised most often as a performance measure?

b. Consider two museums of contemporary art randomly selected from all such museums. Of interest is whether or not the museums use total visitors or funds raised most often as a performance measure. Use a tree diagram to aid in listing the sample points for this problem.

c. Assign reasonable probabilities to the sample points of part b.

d. Refer to parts b and c. Find the probability that both museums use total visitors or funds raised most often as a performance measure.

Stock market participation and IQ.Refer to The Journal of Finance(December 2011) study of whether the decisionto invest in the stock market is dependent on IQ, Exercise3.46 (p. 182). The summary table giving the number ofthe 158,044 Finnish citizens in each IQ score/investment category is reproduced below. Again, suppose one of the citizens is selected at random.

IQ Score

Invest in Market

No Investment

Totals

1

2

3

4

5

6

7

8

9

893

1,340

2,009

5,358

8,484

10,270

6,698

5,135

4,464

4,659

9,409

9,993

19,682

24,640

21,673

11,260

7,010

5,067

5,552

10,749

12,002

25,040

33,124

31,943

17,958

12,145

9,531

Totals

44,651

113,393

158,044

Source:Based on M. Grinblatt, M. Keloharju, and J. Linnainaa, “IQ and Stock Market Participation,” The Journal of Finance, Vol. 66, No. 6, December 2011 (data from Table 1 and Figure 1).

a.Given that the Finnish citizen has an IQ score of 6 or higher, what is the probability that he/she invests in the stock market?

b.Given that the Finnish citizen has an IQ score of 5 or lower, what is the probability that he/she invests in the stock market?

c.Based on the results, parts a and b, does it appear that investing in the stock market is dependent on IQ? Explain.

Male nannies. In a survey conducted by the International Nanny Association (INA) and reported on the INA Web site (www.nanny.org), 4,176 nannies were placed in a job in a given year. Only 24 of the nannies placed were men. Find the probability that a randomly selected nanny placed during the last year is a male nanny (a “mannie”).

Do social robots walk or roll?Refer to the International Conference on Social Robotics (Vol. 6414, 2010) study of the trend in the design of social robots, Exercises 3.10 (p. 168) and 3.37 (p. 181). Recall that in a random sample of 106 social robots, 63 were built with legs only, 20 with wheels only, 8 with both legs and wheels, and 15 with neither legs nor wheels. If a social robot is designed with wheels, what is the probability that the robot also has legs?

Simulate the experiment described in Exercise 3.7 using any five identically shaped objects, two of which are one colour and the three another colour. Mix the objects, draw two, record the results, and then replace the objects. Repeat the experiment a large number of times (at least 100). Calculate the proportion of time events A, B, and C occur. How do these proportions compare with the probabilities you calculated in Exercise 3.7? Should these proportions equal the probabilities? Explain.

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