Question

The Average weight of a class is 27.5. If two students of average weight 35.25 kg, leave the class and two new students of average
weight 33.5 kg join the class, then the average weight of the class becomes 27.4 kg. Find the total no. of students in the class.​

Answer 1

Answer:

35 student

Step-by-step explanation:

27.5n -35.25×2 +33.5×2= 27.4n

27.5n -3.5=27.4n

0.1n=3.5

n=35

Answer 2

Answer:

The total number of students in the class is found to be 35.

Step-by-step explanation:

We know that the equation for finding the mean of a collection of data is:

$\overline x=\frac{Sum\ of\ all\ the\ elements/ data\ samples}{Total\ number\ of\ elements/ data\ samples}$

Let the number of students in the class be $x$,

The average weight of class originally is given as: 27.5 kg,

Then the total weight of students in the class will be: $27.5x$,

Now, we know that two students of average weight 35.25 kg leave and two new students of average weight 33.5 kg join in place of them,

The new average weight of class becomes 27.4 kg,

The new total weight of all students in the class becomes: $27.4x$,

The expression for the total weight becomes:

$27.5x-2(35.25)+2(33.5)=27.4x$

Simplifying it, we get:

$27.5x-27.4x=3.5$

or we can say:

$0.1x=3.5$

$x=35$

Thus, there are 35 students in the class in total.