Question

Average of 5 no.s was 30. when one no. is excluded the average become 28.find the excluded no.

Answer 1

Let the numbers be a,b,c,d,e
a+ b+c+d+e/5 = 30
NOW,
a+b+c+d/4= 28
=>a+b+c+d= 112
and a+ b+ c+ d+ e = 150
=> e= 38.
HOPE IT HELP YOU.

Answer 2

Avg of 5 numbers= 30
Sum total of 5 nos = 30*5 =150
When 1 number is excluded, the avg becomes 28
Sum total of 4 nos = 28*4 =112
So the excluded number = 150-112 = 38

OR
Due to exclusion of 1 number the avg reduced by '2'.
Hence the number is 30 + (2*4) = 38 [ avg+ (change in avg*number of observations)]