Multiple Choice Question
The average of the first three numbers is double of the fourth number. if the average of all the four numbers is 12, find the 4th number.
Explanation:
Let the 4th number be x,
Then the average of first three numbers = 2x ,
So the sum of first 3 numbers = 2x × 3 = 6x,
Since the average of 4 numbers = 12.
Then sum of 4 numbers = 12 × 4 = 48.
so, 48 - 6x = x => 7x = 48,
x = 48/7 ..Ans.
Then the average of first three numbers = 2x ,
So the sum of first 3 numbers = 2x × 3 = 6x,
Since the average of 4 numbers = 12.
Then sum of 4 numbers = 12 × 4 = 48.
so, 48 - 6x = x => 7x = 48,
x = 48/7 ..Ans.
