Question

If 4th and 9th terms of A.P are 12 and 27 respectively, then the values of 'a' and 'd'

Answer 1

Given that ratio is 1:3.

That means, a9 = 3*a4.

Need to find, a12/a5.

a9=a+8d

a4=a+3d

a+8d=3a+9d

d=-2a

a12=a+11d=-21a

a5=a+4d=-7a

So ratio of a12 to a5 = -21a:-7a or 3:1//