
Concept explainers
Counting Methods. Answer the following questions us-
ing the appropriate counting technique. which may be either
arrangements with repetition. permutations. Or combinations.
Be sure to explain why this counting technique applies to the
problem.
23. HOW many different nine-digit ZIP codes can be formed?
24. How many different six-character can formed
from the lowercase letters of the ?
25. HOW many different six-character passwords can formed
from the lowercase letters of the alphabet if repetition is not
allowed?
26. A city council with eight members must elect a
executive committee consisting of a mayor, secretary, and
treasurer. How many executive committees are possible?
27. How many ways can the eight performances at a piano recital
be ordered?
28. A city council with ten members must appoint a four-person
subcommittee. How many subcommittees are possible?
29. Suppose you have 15 CDs from which you 6 CDs to
put in the CD player in your car. If you are not particular
about the order, how many O-CD sets are possible?
30.HOW many 6-person can be formed from a & player
volleyball assuming every player can be assign to
any position?
31. How many different birth orders with respect to gender
possible in a family with five children? (For example.
and BGBGG are different orders.)
32. HOW many different 5-cards can be dealt from a 52-card
deck?
33. How many license plates can be made of the form XX—YYYY,
where X is a letter Of the and Y is a numeral 0—9?
34. How many different groups of balls can drawn from
a barrel containing balls numbered 1—36?
35. How many different telephone numbers of the form aaa-bbb-
cccc formed if the area code cannot contain 0 and
the prefix bbb cannot contain 9?
36. HOW many anagrams (rearrangements) Of the letters
ILOVEMATH can nuke?
37. How many different three-letter “words”- can formed from
the ACGT?
38. The debate club has 18 members, but only 4 can compete
at the next meet. How many 4-Frson teams are possible?
39. A recording engineer wants to make a CD With 12 songs. In
how many different ways can the CD nude?
40. A shelter is giving away 15 but you have
room for only 4 of them. How many different families
could you have?

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Chapter 7 Solutions
Using and Understanding Mathematics: A Quantitative Reasoning Approach (6th Edition)
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- A restaurant serves three fixed-price dinners costing $12, $15, and $20. For a randomly selected couple dining at this restaurant, let X = the cost of the man's dinner and Y = the cost of the woman's dinner. The joint pmf of X and Y is given in the following table. p(x, y) 15 y 12 20 12 0.05 0.10 0.35 x 15 0.00 0.20 0.10 20 0.05 0.05 0.10 (a) Compute the marginal pmf of X. x 12 Px(x) Compute the marginal pmf of Y. y Pyly) 12 15 20 15 20 (b) What is the probability that the man's and the woman's dinner cost at most $15 each? (c) Are X and Y independent? Justify your answer. X and Y are independent because P(x, y) = Px(x) · Py(y). X and Y are not independent because P(x, y) =Px(x) · Pyly). X and Y are not independent because P(x, y) * Px(x) · Py(y). X and Y are independent because P(x, y) * Px(x) · Py(y). (d) What is the expected total cost, in dollars, of the dinner for the two people? $ (e) Suppose that when a couple opens fortune cookies at the conclusion of the meal, they find the…arrow_forwardLet X = the time between two successive arrivals at the drive-up window of a local bank. If X has an exponential distribution with λ = 1, (which is identical to a standard gamma distribution with α = 1), compute the following. (If necessary, round your answer to three decimal places.) (a) the expected time between two successive arrivals (b) the standard deviation of the time between successive arrivals (c) P(X ≤ 1) (d) P(2 ≤ X ≤ 4) You may need to use the appropriate table in the Appendix of Tablesarrow_forwardIn each case, determine the value of the constant c that makes the probability statement correct. (Round your answers to two decimal places.) USE SALT (a) (c) 0.9842 (b) P(0 ≤ Z ≤ c) = 0.3051 (c) P(CZ) = 0.1335 You may need to use the appropriate table in the Appendix of Tables to answer this question.arrow_forward
- QUESTION 4: A college language class was chosen for a learning experiment. Using a list of 50 words, the experiment measured the rate of vocabulary memorization at different times during a continuous 5-hour study session. The average rate of learning for the entire class was inversely proportional to the time spent studying and was given approximately by V'(t) = 15 t 1≤t≤5 Average cost. The total cost (in dollars) of printing x dictionaries is C'(x) = 20,000+ 10x. (A) Find the average cost per unit if 1,000 dictionaries are produced. (B) Find the average value of the cost function over the interval [0, 1,000].arrow_forwardplease include screenshots of all the MATLAB commands and the outputsarrow_forwardPlease include screenshots of MATLAB command and the outputarrow_forward
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