Average
is the sum of observations over a number of observation .In this chapter, we are providing the both normal method and tricks method.
QUES: Average age of 20 students is 16. When the teacher joins the class than the average increases by 1. Then what is the teacher’s age?
ANS: Normal Solutions:
[No. of students × Average Age] – [No. of Students (including teacher) × Average Age (Including Teacher)]= Answer.
Here,
20×16= 320
21×17= 357,
357-320= 37.
Answer is 37.
Shortcut Method:
No. of Students + Average Age + 1 (denotes the teacher) = Answer
= 20+16+1
Answer is 37.
QUES: Average age of 15 students is 12. When the teacher joins the class than the average increases by 1. Then what is the teacher’s age?
ANS:
Normal Solutions:
15×12= 180
16×13= 208
Then, 208-180= 28.
Answer is 28.
Shortcut Trick:
15+12+1= 28.
QUES: Average age of 32 students is 25. When the teacher joins the class than the average increases by 1. Then what is the teacher’s age?
ANS:
Normal Solutions:
32×25= 800
33×26= 858
Then, 800-858= 58.
Answer is 58.
Shortcut Trick:
32+25+1= 58.