The average of twenty- five number is 54. The average of the first 13 numbers and that of the last 13 numbers is 52.8 and 62.2, respectively. If the 13th number is excluded, then what is the average of the remaining numbers (correct to one decimal place)?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 50.2
Average = Sum of observation/ No. of observation.
Sum of twenty five numbers = 25 × 54 = 1350.
Sum of first 13 numbers = 13 × 52.8 = 686.4
Sum of last 13 numbers = 13 × 62.2 = 808.6
13th number = 686.4 + 808.6 - 1350
= 145.
Average of the number when 13th number is excluded,
= (1350 - 145)/24 = 50.2.