What is the first term in a geometric series with ten terms, a common ratio of 0.5 and a sum of 511.5?

Question

I got 256 as my answer.

511.5=a1[1-(.5)^10]/1-1/2
511.5=a1(1023/1024)/1/2
511.5=a1(1023/512) ----> divide by both sides
256=a1

Answer 1

Looks good to me.

You can also check by adding
256 + 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 + 0.5

Answer 2

The first term of a geometric series is 7 and the ratio between terms is 0.5. Find S4.

Answer 3

CAN SOMEONE PLZ TELLME THE ANSWER TO THIS QUESTION Complete the following stepped-out solution to show that 511⋅w⋅115+3 is equivalent to w+3.(1 point)
511⋅w⋅115+3
511⋅
⋅w+3 Commutative Property of Multiplication
⋅w+3 Inverse Property of Multiplication
w+3 Identity Property of Multiplication