Question

If the average (arithmetic mean) of 4,a,b and 6 is 7, what is the value of a+b

Answer 1

The sum of numbers a and b,

i.e., a + b is 18

Explanation:

Given the average (arithmetic mean) of 4, a, b, 6 is 7

Then, according to question,

`((4+a+b+6))/(4) = 7`

4 + a + b + 6 =
`7*4`

10 + a + b = 28

a + b = 28 -10

a + b = 18

Therefore, the sum of numbers a and b, i.e., a + b is 18

Answer 2

a+b=0.7

Explanation:

• The average of a "n" finite serie of numbers can be calculated as
  `average= (1)/(n)*(x_1+x_2+....+x_n)`, being
  `(x_1,x_2,...x_n)` the finite serie of numbers.
• Then, applying this equation to your data, where you have
  `(x_1,x_2,....,x_n)=(4,a,b,6).`, means that
  `7=(1)/(4) *{(4+a+b+6)`.
• This yields in a+b=0.7