The average of 9 results is 45. If the average of the first four results is 44 and that of the last four results is 47, what is the fifth result?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 41
The first four and the last four results together leave out only the fifth result, so the fifth result is the total of all nine minus the totals of the two groups.
Total of the 9 results \(=9\times45=405\)
Total of the first four \(=4\times44=176\)
Total of the last four \(=4\times47=188\)
Fifth result \(=405-(176+188)=405-364=41\)
The fifth result is 41.