Question

the probability that a twelve year old has a brother or sister is 25%. suppose you survey 300 twelve year olds. about how many do you think will have a brother or sister?

Answer 1

n(B U S) = 75

Explanation:

Explanation:-

Probability:-

P(E) =
`(number of elements events in E)/(total number of elementary events in the random experiment)`

`P(E) = (m)/(n)`

Let 'B' be the event of having twelve year old brother

Let 'S' be the event of having twelve year old sister

given data P(BUS) = 0.25

given total survey n(survey) = 300

we have to find the value is n(BUS) =?

we will use probability definition we get, P( BUS) =
`(n(BUS))/(n(survey))`

substitute given values, we will get solution

`0.25 = (n(BUS))/(300)`

after cross multiplication , we get

n(BUS) = 0.25 X 300

n(BUS) = 75