Correct Answer - Option 2 : 12
Given:
In a class average weight of students was 51 kg.
After some days 2 students joined the class
The average was increased by 1.2 kg.
Total weight became 626.4 kg.
Formula used:
Average = Sum of observations/Number of observations
Calculation:
Let number of students before joining 2 students be x
Total weight of x students = 51x kg
After joining of 2 students, total number of students = x + 2
Average weight now = (51 + 1.2) kg
⇒ 52.2
Total weight of (x + 2) students = 52.2(x + 2) kg
52.2(x + 2) = 626.4
⇒ 52.2x + 104.4 = 626.4
⇒ 52.2x = 522
⇒ x = 10
So, total number of students after joining of 2 students = 10 + 2 = 12
∴ The required number of students is 12
