The average weight of the first thirteen persons among fourteen persons is 78 kg. The weight of the 14th person is 39 kg more than the average weight of all the fourteen persons. Find the weight of the 14th person.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 120 kg.
The average weight of the first 13 persons out of 14 persons = 78 kg
The weight of the 14th person is 39 kg more than the average weight of all the 14 persons.
Average = Sum of observation/Number of observations
Let the average weight of all the 14 persons be x kg.
The weight of 14th person = (x + 39) kg
The average weight of 14 persons = (The sum of the weight of all the 14 persons)/14
⇒ x = {(13 × 78) + (x + 39)}/14
⇒ 14x = 1014 + x + 39
⇒ 13x = 1053
⇒ x = 81 kg
he weight of 14th person = (81 + 39) = 120 kg