Question

The mean of 6 observation is 60. If one of the number is excluded , then the mean becomes 45, find the excluded number

• A. 135
• B. 125
• C. 95
• D. 15

Answer 1

The correct option is A

135

The mean of 6 observation is 60

Hence the total sum of 6 observation = 60 $\times$ 6 = 360

The mean of the 5 observation is 45

Hence the total sum of 5 obsevation = 45 $\times$ 5 = 225

The excluded number = Total sum of 6 observation - Total sum of 5 observation

= 360 - 225

=135