Posted by joe on Thursday, December 18, 2008 at 12:22am.
this is a probability question...
Suppose you are asked to choose a whole number between 1 and 13 inclusive.
(a) what is the probability that it is odd?...7/13
(b) What is the probability that it is even?...6/13
(c) what is the probability that it is a multiple of 3?...4/13
(d) what i the probability that it is odd or a multiple of 3?.. This is where i am stumped. the book says the answer is 9/13 but i cant find it.

math probability  Reiny, Thursday, December 18, 2008 at 8:29am
the first 3 are correct
for d)
the odds are 1,3,5,7,9,11,13
multiples of 3 are 3,6,9,12
now the numbers which are either odd OR a multiple of 3 are 1,3,5,6,7,9,11,12,13
or nine of them
so prob = 9/13
There is a formula which says
Prob(A or B) = Prob(A) + Prob(B)  Prob(A and B)
= 4 + 7  2 = 9
notice that the 3 and 9 are in both sets, so if we just add up the count, we counted them twice, so we have to subtract one of the counts.

math probability  gaetan gouninlkpon, Sunday, February 7, 2016 at 6:06pm
P(b and 2)

math probability  dixie, Monday, February 13, 2017 at 4:55pm
help me is suck at math and probability is very hard
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