# Math - Probability 101

In this lecture we look at how to calculate the probability of “mutually exclusive” events.

For your challenge, you were asked to find the probability of drawing either a heart or a face card from a standard deck of 52 playing cards.

Here’s my answer for the challenge

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Great work @valyfox!

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1. there are 13 hearts => 13/52
2. there are 12 face cards (3 cards per suit times 4 suits) => 12/52
3. 3 face cards are also hearts (13/52 * 12/52 = 3/52)

P(A|B) = P(A) + P(B) - P(A&B)
P(A|B) = (13/52 + 12/52) - 3/52
P(A|B) = 25/52 - 3/52
P(A|B) = 22/52 = 11/26

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here is mine:

(12/52)+(13/52)-((12/52)*(13/52))
(25/52)-(3/52)
22/52=.423=42.3%

13/52 + 12/52 + 13 * 12 / 52 * 52
13 / 52 + 12/52 + 3/52
r = 22/52 = 0.42 = 42%

13\52+4\52-3\52 = 0.42 so the probability is 42%

(13/52) + (12/52) - (3/52) = 22/52

This is around a 42.3% chance.

(13/52)+(4*3)/52-(3/52)=(13+9)/52=22/52=0.4231

P(Heart or Face) = P(Heart) + P(Face) - P(Heart and Face)

P(Heart) = 13/52
P(Face) = 12/52
P(Heart and Face) = 13/52 * 12/52 = 3/52

P(Heart or Face) = 13/52 + 12/52 - 3/52
= 22/52 = 0.423 = 42.3%

P(Heart || Face) = P(Heart) + P(Face) - P(Heart & Face) = (13 + 3*4 - 3)/52 = 22/52 = 42.3%

P(HF) = 13/52 + 12/52 - (13/52 * 12/52)
P(HF) = 25/52 - 3/52 = 11/26 = 0.423 = 42.3%