The table shows information about some children. Age 11 Age 12 Total
Girls 3
a
b
Boys
c
5 8
Total
d
13
e

A pupil is selected at random.
What is the probability of selecting a student aged 12?
Give your answer in its simplest form.

Step-by-step explanation:

Given

        Age 11    Age 12    Total  

Girls   3             5              8

Boys   1             3             4

Required

The number of aged 12 children is:

The total number of children is:

So, we have:

Simplify

1.4

2.3

step-by-step explanation:

the formula for the constant of variation is

y= kx

divide each side by x

y/x =kx/x

y/x =k

we know a and y

1.   y/x = k

4/1 =4

check the other values to make sure they are the same

8/2 = 4   12/3 =4   and 16/4 =4  

the constant of variation is 4

2.   y/x = k

3/1 =3

check the other values to make sure they are the same

6/2 = 3   9/3 =3   and 12/4 =3  

the constant of variation is 3