Question

the average age of 3 student is 15 years. if the 1st student is 18 years old and 2nd student is 12 years then, find of age of the 3rd student.​

Answer 1

let , the age of 3rd student is X

so, according to the statement we get,

(18 + 12 + X) / 3 = 15

=> (30 + X) = 45

=> X = 15

so, the age of the 3rd student is 15 years