Question

the average age of a class of 40 boys is 11.5 years. the average of the class is raised to 12 years by the coming of a new boy. how old is the new boy?​

Answer 1

Answer:

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Step-by-step explanation:

The average age of 30 students is 9 years. If the teacher included the average becomes 10 years. What is the age of the teacher?

Soln. :

Average age of 30 students=9

Total age of 30 students = 30 ×9=270 (1)

Average including teacher (31 person, 30 students + 1 teacher) =10

Total age including teacher=31×10=310

Age of 30 students + age of teacher =310

By(1) Replace Age of 30 students with 270

270 + Age of teacher = 310

Age of teacher =310–270=40. Ans….

Answer 2

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