Question

average of 9 number is 20 if a number 30 is also included then what will be the average of these 10 numbers​

Answer 1

Step-by-step explanation:

30 = 20 +10

30 is 10 more than average value

so new average increased by

10/no. of values =10/10 =1

so now avg of 10 values =20+1=21

for me this is the easiest way

Alternatively

avg of 9 =20

sum of 9=9×20=180

new sum =180+30=210

new avg= sum of values/no. of values =210/10

=21