Question

Average age of a group of 10 students is 12 years if 5 new students join them then the average age of the group increase by 1 year the average age of the new students is
A 13 year
B 15 year
C 16 year
D 18 year​

Answer 1

Total age of 10 students = 150 years

Total age of 15 students = 240 years

Total age of 5 new students = 240 - 150 = 90 years

\inline \therefore Average age of 5 new students =  = 18 years

Answer 2

Answer:

Option B

15 years

Step-by-step explanation:

Given:-

Average age of a group of 10 students is 12 years if 5 new students join them then the average age of the group increase by 1 year.

To find:-

Find the average age of the new students ?

Solution:-

Average age of group of 10 students = 12 years

Average= Sum of all observations/Number of all observations

=>Sum of all ages = 12×10 = 120 years

Number of students are joined = 5

Then, Total number of students = 10+5 = 15

Then The average of total students = increased by 1 year = 12+1 = 13 years

sum of ages of all 15 students = 15×13 = 195

Sum of ages of new 5 students =

Sum of ages of all 15 students - Sum of ages of 10 students

=>195-120

=>75

Sum of ages of new students =75

Average =Sum of all observations/Number of all observations

=>Average = 75/5

Average = 15 years

Answer:-

The average age of the new 5 students = 15 years

Used formula:-

Average =

Sum of all observations/Number of all observations