Select the correct answerOut of a class of 64 people ,7 people of average weight 61 kg leave, and immediately 3 people weighing 70kg ,77 kg and 68 kg join. there by making the new average weight of the class 69 kg. What was the original average weight of the class of 64 people?Options9059677068

To solve this problem, we need to use the formula for average weight, which is the total weight divided by the number of people.

Step 1: Calculate the total weight of the class after the changes. This is done by multiplying the new average weight by the new number of people in the class.

69 kg (new average weight) * 60 people (new number of people) = 4140 kg (total weight after changes)

Step 2: Calculate the total weight of the people who left and the people who joined.

7 people * 61 kg (weight of people who left) = 427 kg (total weight of people who left)

70 kg + 77 kg + 68 kg (weights of people who joined) = 215 kg (total weight of people who joined)

Step 3: Calculate the original total weight of the class. This is done by adding the weight of the people who left to the total weight after changes and subtracting the weight of the people who joined.

4140 kg (total weight after changes) + 427 kg (weight of people who left) - 215 kg (weight of people who joined) = 4352 kg (original total weight)

Step 4: Calculate the original average weight. This is done by dividing the original total weight by the original number of people.

4352 kg (original total weight) / 64 people (original number of people) = 68 kg (original average weight)

So, the original average weight of the class of 64 people was 68 kg.