Question

In a class with a certain number of students, if one student weighing 50 kg is added then the average weight of the class increases by 1 kg. If one more student weighing 50 kg is added then the average weight of the class increases by 1kg. If one more student weighing 50kg is added then the average weight of the class increase by 1.5 kg over the original average. What is the original average weight (in kg) of the class. ?

• A. 4
• B. 46
• C. 2
• D. 47

Answer 1

The Correct Option is D

Let's take the number of students in class be n and average weight be A kgs and let's take the sum of ages of all students be S
So, ∑\(\frac{S}{n}\) = A
∑S + \(\frac{50}{n+1}\) = A + 1
∑S + 50 + \(\frac{50}{n+2}\) = A + 2
∑S + 50 + 50 + \(\frac{50}{n+3}\) = A + 3.5
After solving the above equations, we get the value of A i.e.
A = 47
The correct option is (D)