Question

In a shopping mall with a staff of 5 members the average age is 45 years. After 5 years a person
joined them and the average age is again 45 years. What's the age of 6th person?
25
30
20
10​

Answer 1

Answer:

Step-by-step explanation:

let the age of five  members be a, b, c, d, e years

(a+b+c+d+e)/5 =45    

a+b+c+d+e = 5x45 =225

a+b+c+d+e = 225             equation 1

after 5 years

age of each member be a+5, b+5, c+5, d+5, e+5

let the age of 6th person be p years

(a+5+b+5+c+5+d+5+e+5+p)/6 = 45

a+b+c+d+e+p+25 = 6x45 =270

a+b+c+d+e+p =270 -25 = 245

putting equation 1

225 + p = 245

p =245 -225

p= 20 years