**Problem 1:** The average of 5 numbers is 52. If one number is excluded, the average becomes 50. Find the excluded number?

Solution:

Sum = 52*5 = 260

Sum = 50*4 = 200

260-200 = 60

Shortcut

52+4*2=60

**Problem 2:** The average age of 30 students is 12 years. When the teacher’s age is included in it, the average increased by 1. What is the teacher’s age?

Solution:

12+31*1=43

**Problem 3:** Average marks 0f 22 students is 75. The average is reduced by 2 if we exclude the highest and lowest marks. Find the sum of the highest and lowest marks?

Solution:

75*2+2*20 = 150+40 =190