Question

Question #a920f

Answer 1

`b) -> 8.75`

Explanation:

Out of 44

`9/44xx10=2.045bar(45)larr 2 1/22`

`15/44xx9=3.0681bar81larr 3 3/44`

`20/44xx8=3.63bar63 larr 3 7/11`

The 'Expectation' (mean value) is `8 3/4`

Answer 2

Mean = `385/44 = 8.75` years

Explanation:

To find the mean of a set of date we use the following method:

`Mean = ("sum of all the values")/("the number of values") = "total"/"number" or " M=T/N`

Remember, we can add numbers, we can add totals,
WE CANNOT ADD MEANS!

For the 44 boys in the class , we can find the sum of all their ages.

9 boys are all 10 years old, the sum of their ages is `9 xx10 = 90`
15 boys are all 9 years old, the sum of their ages is `15 xx 9 = 135`
20 boys are all 8 years old:, the sum of their ages is `20 xx 8 = 160`

`90+135+160 =385`

For the 44 boys, the sum of their ages is 385 years.

Mean = `385/44 = 8.75` years