Question

The average weight of a group of 25 students increases by 1 kg when their teacher joins the group. If the initial average of the group of 25 students was 30 kg, find the weight of the teacher?

Answer 1

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We have to find weight of Teacher ?

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Method (1) :--

We know that ,

$average = \frac{total \: sum}{no. \: of \: observation}$

so, Total weight of All students = 25 × 30 = 750kg.

After a teacher came new average was increased by 1 kg , so new average of 26 members now = 31

so, their total weight = 31 × 26 = 806 kg

so, weight of Teacher = 806 - 750 = $\large\red{\boxed{\sf 56\:Kg}}$

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Method (2) :---

Teacher weight = New average +[ Total students × increased average ]

Teacher weight = 31 + [25 × 1] = 31 + 25 = $\large\red{\boxed{\sf 56\:Kg}}$

Answer 2

$<font color ="red">$ ✨ ANSWER ✨

$<font color ="blue">$ ✨ 56KG ✨

Step-by-step explanation:

Total number of students = 25

Average weight of 35 students = 25 Kg

So total weight of all 35 students = 25×30 Kg

= 750 Kg

Now,if a teacher is included,

Total no of students & teacher = 25+1= 26

Since after including a teacher,average weight increases by one,

So average weight of students &teacher=26Kg

=> Total weight of students & teacher = 26×31

= 806 Kg

So the difference of total weight after adding a teacher = 806 - 750 = 56 Kg