There are five numbers. The average of the first four numbers is 5/6 off the fifth number. If the average of all the five numbers is 26, then what is the fifth number?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 30.
Average of all the five numbers = 26
The average of the first 4 numbers is 5/6 of the fifth number.
Average = Sum of elements/Number of elements
Let the fifth number be 6x.
So, the average of the first four numbers = 6x × 5/6
According to the question -
5x × 4 + 6x = 26 × 5
20x + 6x = 130
26x = 130
x = 130/26
x = 5
Fifth number = 6 × 5 = 30