Q7. There are 15 children at a birthday party.
The mean age of the 15 children is 7 years.
9 of the 15 children are boys.
The mean age of the boys is 5 years.
Work out the mean age of the girls.

Mean of the girls is 9?

Step-by-step explanation:

5 + 9 =

14 / 2 = 7

10

Step-by-step explanation:

Let c = sum of ages of all children.

mean age of all children = c/15 = 7

c = 15 * 7 = 105

The sum of the ages of all children is 105.

Let b = sum of ages of the 9 boys.

mean age of boys = b/9 = 5

b = 9 * 5 = 45

The sum of the ages of the boys is 45.

The sum of the ages of the girls is c - b.

c - b = 105 - 45 = 60

The number of girls is 15 - 9 = 6

mean age of girls = (sum of ages of the girls)/(number of girls) =

= 60/6 = 10

circle area = pi * radius^2

if diameter = 10 then radius = 5

circle area = pi * 5^2

circle area = pi * 25

circle area = 78.5398163397 square units

step-by-step explanation:

(f - g)(x) = 5x^3 - 3

step-by-step explanation:

rearrange these functions vertically, with like terms in separate columns:

f(x) = 5x^3 - 2

g(x) =         +1

now subtract, column by column:

(f - g)(x) = 5x^3 - 3