Question

The average of 4 number is 12 and that of first three is 11 fond the fourth number

Answer 1

Answer:

The fourth number is 15

Step-by-step explanation:

Average = Sum of observations / No. of observations

Average of four numbers = 12

=> Sum of four numbers = 4*12 = 48

Average of first three numbers = 11

=> Sum of first three numbers = 3*11 = 33

Let "x" be the fourth number. Clearly,

Sum of all four numbers = Sum of first three numbers + x

48 = 33 + x

x = 48 - 33

x = 15

Verify:

Sum of first three numbers = 33

Fourth number = 15

Sum of all four numbers = 33+15 = 48

Average of all four numbers = 12 (as given)