CGPET 2014 Solved Paper

Let four terms in a GP be ar3,ar,‌

a

r

and ‌

a

r3

.
According to the given condition,
‌ar3+ar+‌

a

r

+‌

a

r3

=60 . . . (i)
and ‌‌

ar3+ a r3

2

=18
‌⇒‌‌ar3+‌

a

r3

=36 . . . (ii)
‌
Now, from Eq. (i), we have
‌(ar+‌

a

r

)+ar3+‌

a

r3

‌=60
⇒a(r+‌

1

r

)+36‌=60 [from Eq. (ii)]
⇒a(r+‌

1

r

)‌=24 . . . (iii)

On dividing Eq. (iii) by Eq. (ii), we get
‌

a(r3+ 1 r3 )

a(r+‌ 1 r )

=‌

36

24