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

Answer:

n(B U S) = 75

Step-by-step explanation:

Explanation:-

Probability:-

P(E) = $\frac{number of elements events in E}{total number of elementary events in the random experiment}$

$P(E) = \frac{m}{n}$

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) =$\frac{n(BUS)}{n(survey)}$

substitute given values, we will get solution

$0.25 = \frac{n(BUS)}{300}$

after cross multiplication , we get

n(BUS) = 0.25 X 300

n(BUS) = 75