Question

the mean of 3 numbers is 4 two of the numbers are 1 and 9 what is the 3rd number?

Answer 1

Let that number be x!

Mean=(sum of observation) /(total number of observations)

So here, 4=(x+1+9)/3

4*3=(10+x)

12=10+x

X=12-10=2.......

X=2

Hope it helps!! :)

Answer 2

two numbers are 1,9

the mean of 3 numbers is 4

sum of three numbers /total number = mean

=>(1+9+3rd number)/3 = 4

=> 1+9+3rd number= 12

=> 3rd number= 12-10

3rd number= 2