An old student of weight 25 kg was replaced by the new student due to

1.	An old student of weight 25 kg was replaced by the new student due to which average weight of class of 15 students increased by 2 kg. Find the weight of new student?1. 55 kg2. 45 kg3. 50 kg4. 30 kg
Answer» Correct Answer - Option 1 : 55 kg Given: There are total 15 students in a class. An old student of weight 25 kg was replaced by the new student. New average weight is more than the old average weight by 2 kg. Concepts used: Average weight = (Total weight of all students)/(Number of students) Calculation: Let the original average weight of students be x kg. So, Total weight of all students = 15x According to the question New average weight = x + 2 kg Let the weight of the new student be y kg. New total weight of 15 students = Original total weight of all students + Weight of new student - weight of old student ⇒ (15x + y – 25) kg Average weight = Total weight of all students/Number of students ⇒ x + 2 = (15x + y – 25)/15 ⇒ 15 × (x + 2) = 15x + y – 25 ⇒ 15x + 30 = 15x + y – 25 ⇒ y = 30 + 25 = 55 kg ∴ The weight of new student is 55 kg.

An old student of weight 25 kg was replaced by the new student due to which average weight of class of 15 students increased by 2 kg. Find the weight of new student?1. 55 kg2. 45 kg3. 50 kg4. 30 kg

Answer» Correct Answer - Option 1 : 55 kg

Given:

There are total 15 students in a class.

An old student of weight 25 kg was replaced by the new student.

New average weight is more than the old average weight by 2 kg.

Concepts used:

Average weight = (Total weight of all students)/(Number of students)

Calculation:

Let the original average weight of students be x kg.

So, Total weight of all students = 15x

According to the question

New average weight = x + 2 kg

Let the weight of the new student be y kg.

New total weight of 15 students = Original total weight of all students + Weight of new student - weight of old student

⇒ (15x + y – 25) kg

Average weight = Total weight of all students/Number of students

⇒ x + 2 = (15x + y – 25)/15

⇒ 15 × (x + 2) = 15x + y – 25

⇒ 15x + 30 = 15x + y – 25

⇒ y = 30 + 25 = 55 kg

∴ The weight of new student is 55 kg.