probability

Question

a number smaller than 25 is chosen at random. find the probability of choosing: a factor of 20, an even number or a 7, a number smaller than 15

Answer 1

Sample Space

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,,20,21,22,23,24

the sample space consists of 24 numbers

 

P(a factor of 20)=6/24=1/4 (factors of 20 are 1,2,4,5,10,20)

P(an even number or a 7)=13/24 (there are 12 even numbers and 1 seven)

P(a number smaller than 15)=14/24=7/12 (there are 14 numbers smaller than 15)