Question

the sum of three numbers in AP is 12 and the ratio of first number to third number is 1:3 find the numbers​

Answer 1

let k be the reqd ratio

a3 = 3k ; a = k

S3 = [ a + l ] n /2

=> 12 = (3k + k) . 3/2

=> 12*2/3 = 4k

=> 8 = 4k => k = 2

therefore, a = 2, a3 = 6

( here in ap a is first term and a3 is third term)