The mean of 5 numbers is 15. If one more number is included, the mean of the 6 numbers becomes 17. Find the included number.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 27
Mean \(\times\) number of values gives the total of the values. Adding one number changes the total by that number, so the included number is the increase in the total.
Total of the first 5 numbers is \(5\times15=75\)
Total of all 6 numbers is \(6\times17=102\)
The included number is the difference, \(102-75=\) 27