Answers to Sections 3 and 4 of Marcel B. Finan's "A Probability Course for the Actuaries"

G. Stolyarov II
These answer keys are meant to assist students using Marcel B. Finan's A Probability Course for the Actuaries. With Dr. Finan's permission, Mr. Stolyarov wrote solutions for the problems in his study guide and is endeavoring to make the answer keys to each section publicly available. You can see his full List of Answer Keys here. Do the problems at the end of each section and then check your answers with these keys.

Dr. Finan's study guide is an excellent resource for those preparing to take Actuarial Exam 1/P on probability.

Problems that require numerical answers are answered here, but it is still the responsibility of the student to provide his or her own work for these problems. These answers are meant to enable students to independently verify the correctness of their reasoning by checking to see if the end result they obtained is correct. Questions from the study guide that require proofs or diagrams are not addressed here, as the end result of those questions is known in advance, and it is the responsibility of the student to provide the procedure for getting there.

Section 3.

Answer 3.1a. 100 ways

Answer 3.1b. 900 ways

Answer 3.1c. 5040 ways

Answer 3.1d. 90000 ways

Answer 3.2a. 336 finishing orders

Answer 3.2b. 6 finishing orders

Answer 3.3. 6 choices of outfits

Answer 3.4. 90 ways

Answer 3.6. 36 ways

Answer 3.7. 380 ways

Answer 3.8. 6,497,400 ways

Answer 3.9. 5040 ways

Answer 3.10. 3840 ways

Section 4.

Answer 4.1. m=9 and n=3

Answer 4.2a. 456,976 words

Answer 4.2b. 358,800 words

Answer 4.3a. 15,600,000 possible license plates

Answer 4.3b. 11,232,000 possible license plates

Answer 4.4a. 64,000 possible combinations

Answer 4.4b. 59,280 possible combinations

Answer 4.5a. 479,001,600 arrangements

Answer 4.5b. 604,800 arrangements

Answer 4.6a. 5

Answer 4.6b. 20

Answer 4.6c. 60

Answer 4.6d. 120

Answer 4.7. 20 ways

Answer 4.8a. 362,880 ways

Answer 4.8b. 15,600 ways

Answer 4.9. m=13; n=1 or n=12

Answer 4.10. 11,480 possible choices

Answer 4.11. 300 handshakes

Answer 4.12. 10 ways

Answer 4.13. 28 ways

Answer 4.14. 4060 ways

Answer 4.15. The number of permutations of a set of objects is usually greater.

Answer 4.16. 125,970 possible juries

Answer 4.17. 14/2!= 43,589,145,600 ways

Answer 4.18. 144 ways

See a list of all the answer keys to Dr. Finan's study guide for Exam 1/P here.

Published by G. Stolyarov II

G. Stolyarov II is a science fiction novelist, independent essayist, poet, amateur mathematician, composer, author, and actuary.  View profile

3 Comments

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  • G. Stolyarov II1/1/2010

    The correction to the answer to Problem 4.17 has now been made. Thank you, Joe and Frank, for your feedback.

  • Joe12/24/2009

    I agree with Frank. The answer should be 14!/2 because the circular band can be simply flipped over. Both of these combinations of pearls would be the same and this rule would apply for all 14! of the combinations. So 14!/2 is how many different combinations there actually are.

  • Frank3/20/2009

    On question 4.17 I think you have overlooked a fundamental
    symmetry in your solution. This is of course a matter of
    interpretation but given the physical reality of the circumstance I
    think it is reasonable to assume that the action of picking up the
    band and flipping it over does not structurally alter it in any
    fundamental way. Therefore any two outcomes which would be reflections
    of one another along any axis of symmetry should be considered
    fundamentally the same in this example. As such rather than having our
    outcome invariant under action of the cyclic group, it is invariant
    under action of the dihedral group D_{30}. So we have the following
    short exact sequence.

    0-->D_{30}-->S_{15}-->X-->0

    Where X is our space of outcomes gifted with an inheirited, but
    irrelevant, group structure from S_{15}.

    In any case |X|=|S_{15}|/|D_{30}|= 15!/30=14!/2

    This is a nice generalization to the circle permutations.

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