The given GP is .→ (1)

The first term in the GP,

The second term in the GP,

The common ratio,r = 3

The last term in the given GP is a_n = 162.

Second last term in the GP = a_n-1 = ar^n-2

Starting from the end, the series forms another GP in the form,

ar^n-1, ar^n-2, ar^n-3….ar³, ar², ar, a → (2)

Common ratio of this GP is .

So,.

So, 4^th term of the GP (2),

a₄ = ar³

=

Hence, the 4^th term from the end of the given GP is 6.