Question #a920f

2 Answers
Jul 25, 2016

Answer:

#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#

Aug 23, 2016

Answer:

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