Let the common ratio be r.
If the first is the least, then terms are 1, r and r².
If the last is the least, the terms are 1/r² , 1/r and 1
using statement I,
1+r+r² =21 ⇒ r² + r - 20 = 0
(r + 5)(r - 4) =0 ⇒ r=-5 or 4
If r = - 5 then the numbers are, 1, -5 and 25, but least among them is - 5 ⇒ r ≠ -5
Hence, r = 4 (we may check for the consistency here also)
So, statement I is sufficient
using statement II (r)(r²) = 64
r³ =64 ⇒ r=4
∴ Using middle term is 4; So, the statement II is sufficient.
Let the common ratio be r.
If the first is the least, then terms are 1, r and r².
If the last is the least, the terms are 1/r² , 1/r and 1
using statement I,
1+r+r² =21 ⇒ r² + r - 20 = 0
(r + 5)(r - 4) =0 ⇒ r=-5 or 4
If r = - 5 then the numbers are, 1, -5 and 25, but least among them is - 5 ⇒ r ≠ -5
Hence, r = 4 (we may check for the consistency here also)
So, statement I is sufficient
using statement II (r)(r²) = 64
r³ =64 ⇒ r=4
∴ Using middle term is 4; So, the statement II is sufficient.