josie is about to draw a card at random from a standard deck of 52 playing cards. determine the probability that she will draw a red card or a 7.

a) 1/2 b) 1/13 c) 7/13 d) 15/26

thank you

3 answers

pr(red or 7)=Pr(red)+Pr(7) - pr(red and 7)
= 1/2 + 4/52 - 2/52= (26+4-2)/52=28/52=7/13
there are 26 red cards (half the deck), plus two black 7's

(26 + 2)/52 ... reduce the fraction
28/52 reduces to 7/13 since both are reducible by 4 the equation to remember is P(Q/total) meaning that the probability of in this case red cards or a 7 and the total of cards goes under the Q THERE SHOULDN'T BE A PROBABILITY OVER 100%!!!!!!!