Question

Out of the five numbers average of first four numbers us 15 and the average of last 4 numbers is 12 .also last number is 18 .what is the first number

Answer 1

let the numbers be a,b,c,d and e=18 {given}

(a+b+c+d)/4=15

a+b+c+d=60

∴a=60-(b+c+d)

(b+c+d+e)/4=12

b+c+d+e=48

b+c+d+18=48

∴b+c+d=48-18=30

a=60-(b+c+d)

a=60-30

∴a=30