Answer:
11 years old
Step-by-step explanation:
If four brothers have the average age 6, then the sum of their ages is

years.
Let x years be the age of sister. If four brothers and their sister have the average age 7, then

Multiply this equation by 5:

The sister is 11 years old.
Part A:
3.14 X (4)^2 X 3/3
= 50.26548246
Step-by-step explanation:
uiuhhhghjsjsisbsidgurdbridbr d
48/60 = .8
This means 80% of 60 is equal to 48.
Thus, a0% = 80%
and we can determine that a = 8.