Question

Find the average of first 50 even number

Answer 1

first 50 even numbers
are 2,4,6,.........,98,100

mean = sum of observation /no. of observation

sum of observation = 2+4+6......+98+100 = 2(1+2+3......+50)
since sum of n natural no. = n(n+1) /2

so (1+2+3......+50) = 50*51/2

so sum = 2*50*51/2 = 50*51
no. of observation = 50

thus mean = 50*51/50 = 51

Answer 2

here is the solution