LIVE Course for free

Rated by 1 million+ students
Get app now
JEE MAIN 2023
JEE MAIN 2023 TEST SERIES
NEET 2023 TEST SERIES
NEET 2023
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
24 views
in Aptitude by (53.1k points)
closed by
Average age of class of 72 students is 20 years. Two girls of age 20 and 22 years leave the class and a new boy joins. If new average age is same as previous one then find age of new boy.
1. 22
2. 20
3. 18
4. 14

1 Answer

0 votes
by (54.5k points)
selected by
 
Best answer
Correct Answer - Option 1 : 22

Given:

72 students = 20 years (Average age)

Two girls removed – 20 and 22 age

New average = 20 years

Formula used:

Average of X = (X1 + X2 + X3 + X4….. + Xn)/ n

Calculation:

Average of 72 = 20

⇒ Total age of 72 students = 72 × 20

⇒ Total age of 72 students = 1440

⇒ Two girls removed = 1440 – (20 + 22)

⇒ Two girls removed = 1398

Now, let age of new boy be X

⇒ Total number of students = 70 + 1 (New boy added)

⇒ Total age of 71 students = 71 × 20

⇒ Total age of 71 students = 1420

⇒ Total age of 71 students = 1398 + X

⇒ 1398 + X = 1420

⇒ X = 22

∴ Age of new boy is 22

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...