Two geometric means are inserted between 6 and 384 so the four numbers form a geometric sequence. What are these two numbers?

an = a1(r)n − 1=384=6(r)^4-1=4 common ratio.

The common is 4 and so we have:

6, 24, 96, 384..................................

The answer is C.

384/6 = r³

64  = r³       take the cube root of each side

4 = r

So the second number  = 6(4)  = 24

And the third = 24(4)  = 96