The average of three numbers a, b and c is 2 more than c. The average of a and b is 48. If d is 10 less than c, then the average of c and d is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 40
Concept
Average = Sum of observation / No of observations
Application
Average of a, b, c = ( a + b + c) / 3
According to the question
( a + b + c) / 3 = c + 2
Average of a and b = 48
It means sum of a and b = 48 x 2 = 96
Putting the value of a + b = 96 in ( a + b + c) / 3 = c + 2
a + b + c = 6 + 3c
96 + c = 6 + 3c
2c = 90
c = 45
d = 45 - 10 = 35
Average of c and d = (45 + 35) / 2 = 40