Aptitude Shortcut methods and tricks for Average Problems

Average age of 20 students is 16. When the teacher joins the class then the average increases by 1. Then what is the teacher’s age?

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.

For this it will take hardly 20 to 25 seconds. But using the below Shortcut trick you can solve this problem within 3 seconds.

Shortcut Method:

No. of Students + Average Age + 1 (denotes the teacher)= Answer

= 20+16+1

Answer is 37.

Examples: 1. Average age of 15 students is 12. When the teacher joins the class then the average increases by 1. Then what is the teacher’s age?

Solution: 15×12= 180

 16×13= 208 Then, 208-180= 28.

 Answer is 28.

Shortcut Trick:

15+12+1= 28. 2. Average age of 32 students is 25. When the teacher joins the class then the average increases by 1. Then what is the teacher’s age?

 Solution:

32×25= 800

33×26= 858

Then, 800-858= 58.

Answer is 58.

Shortcut Trick:

 32+25+1= 58.

Model Question:- Average age of 20 students is 16. When the teacher joins the class then the average increases by 1. Then what is the teacher’s age? Normal Solutions: [No. of students × Average Age] – [No. of Students (including teacher) × Average Age (Including Teacher)]= Answer.

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