Question

Find the mean of first 20 multiples of 5

Answer 1

Step-by-step explanation:

PLEASE MARK AS BRAINLY

Answer 2

Answer: 52.5

Step-by-step explanation:

First 20 multiples of 5 are, 5,10,15, 20,25,...........,90,95,100

Mean= [5+10+15+......... +90+95+100]/20

= 5×[1+2+3+4+...+18+19+20]/20

=[1+2+3+4+..... +18+19+20]/4

But, 1+3+3+4+.....+n= n(n+1) /2,

1+2+3+4+..... +18+29+20=

=20(20+1) /2=210

So,

[1+2+3+4+..... +18+29+20]/4= 210/4= 52.5