I have some questions about counting principles in mathematics:(adsbygoogle = window.adsbygoogle || []).push({});

If I had standard deck of 52 playing cards, then

a. How many ways can one draw a heart or a space?

b. " " an ace or a king?

c. " " a card numbered 2 through 10?

d. " " a card numbered 2 through 10 or a king?

I got these answers (using the addition rule of a disjoint union and the multiplication rule):

a. Let A = cards that are hearts and B = cards that are spades.

|A| + |B| = 13 + 13 = 26

b. Let A = aces and B = kings

|A| + |B| = 4 + 4 = 8

c. Let A = {2, 3, 4, ... 10 belonging to hearts}, B = {2...10 belonging to spades}, C = {2...10 belonging to diamonds}, and D = {2...10 belonging to clubs}

|A| + |B| + |C| + |D| = 9 + 9 + 9 + 9 = 36

d. Take previous answer and add to 4 (Let E = kings):

36 + |E| = 40

Am I correct as far as using these rules? Thanks.

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# Counting math

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