Binomial Distribution and Probability - Statistics

A study concerning the relative influence of husbands and wives in consumer purchasing, which appeared in recent issue of Time Magazine, reported that husband exerts the primary influence in selecting the make of a new automobile in about 70% of all new-car purchases by families. Suppose five families have decided to buy a new car.

a. What is the probability that in exactly two of the five families the husband will exert the primary influence in choosing the make of a car?

b. What is the probability that the husband will select the make of car in all five families?

c. What is the probability that the husband will exert the primary influence in choosing the make of a car in at least three of the five families? Use Binomial Table given in Appendix B (Text) for this section.

What I have so far:

Binomial Distribution: n = 5, p = .7, q = .3

a) x = 2

I used the Binomial Distribution Formula

I got .1323

b) x = 5

I used the same Binomial Distribution Formula

I got .16807

c) I don't know how to do this one. If anyone can please help me, I would appreciate it. I tried to look at the Binomial Table and it asked me for k. How do I find k? Also, I am aware there is no Appendix B. Please just use the Binomial Table

Also, Please let me know if a and b are correct.

Thank you.

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(a) and (b) are correct. (c) is just $P(3) + P(4) + P(5)$, which is the sum of probabilities of exactly 3, exactly 4 and exactly 5. –  Tunococ Oct 27 '13 at 23:02
ok Thank you! :) –  Shaily Oct 27 '13 at 23:12