in a geometric sequence, the fourth term is 8 times the first term. the sum of the first 10 terms is 2557.5. find the 10th term of this sequence.

1,280

Step-by-step explanation:

Let's find out the multiplier, and since it is 8 times the first term, then it is 2.

That is you will have x, 2x, 4x, 8x

So the first 10 terms are x, 2x, 4x, 8x, 16x, 32x, 64x, 128x, 256x, 512x

The sum is 1023x, which is also 2557.5

Which makes x=2.5

And the 10th term is 512*2.5=1,280