Question

Evaluate

Answer 1

\[\sum_{n=3}^{12}20(0.5)^{n-1}\]

Answer 2

Geometric

Answer 3

You want to find the sum of the first 3 terms?

Answer 4

no the sum of all 13 numbers

Answer 5

Did you get an answer of 40

Answer 6

I might be wrong

Answer 7

\[20\sum_{n=2}^{12}(\frac{ 1 }{ 2 })^{n-1}=20\frac{ 1-(\frac{ 1 }{ 2 })^{11} }{ 1-0.5 }\] That's the sum of a geometric series. I think you can do the rest !

Answer 8

Yes I can but if i give a number i get can you tell me if its right or wrong?

Answer 9

-39.980

Answer 10

?

Answer 11

Should be 40. No negative sign

Answer 12

You'll get 40 if you round it up

Answer 13

9.99

19.95

29.98

39.96
these are the options

Answer 14

The last one

Answer 15

@Chad123 is correct

Answer 16

thank you both of you guys! chad can you give math&ing a medal and ill give you one

Answer 17

I actually did thanks guys

Answer 18

Math ing can you pls come to my new question?