Q. 104.8( 4 Votes )

# The mean of 5 numbers is 20. If one number is excluded their mean is 15. Then the excluded number isA. 5B. 40C. 20D. 10

Given that, Total number of observations = 5

Mean = 20

So, Sum of observations can be given as

Sum of observations = Mean × Total number of observations [ ]

Sum of observations = 20 × 5

Sum of observations = 100

Let the excluded number be x.

New Sum of observations = 100 – x

New Mean = 15

New total number of observations = 4

Mean is given by

100 – x = 15 × 4

100 – x = 60

x = 100 – 60 = 40

The excluded number is 40.

Thus, option (B) is correct.

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Quiz | Median and Mode29 mins
Quiz | Basics of Mean37 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses