Question

The population of a local species of flies can be found using an infinite geometric series where a1 = 940 and the common ratio is . Write the sum in sigma notation and calculate the sum (if possible) that will be the upper limit of this population.

Answer 1

PLEASE HELP :(

Answer 2

@kc_kennylau

Answer 3

What's the common ratio?

Answer 4

\[\Sigma=\frac{a_1}{1-r}\]

Answer 5

1/5

Answer 6

one fifth is the common ratio

Answer 7

Use the formula that I just gave you

Answer 8

alright give me a sec

Answer 9

whats r?

Answer 10

The common ratio

Answer 11

Okay I shouldn't have used \(\Sigma\) as the sum

Answer 12

im completely lost im sorry

Answer 13

The sum \(S\) of a geometric series with the first term being \(a_1\) and the common ratio being \(r\) is given by the formula \(S=\dfrac{a_1}{1-r}\)

Answer 14

ok

Answer 15

4699/5?

Answer 16

And if you have to write it in sigma notation, \(\displaystyle\Large\sum_{n=1}^\infty a_1r^{n-1}\)

Answer 17

939.8

Answer 18

Nope, 939.8 isn't what I got, mind showing us your steps?

Answer 19

um yea i divided 940 by 1 minus 1/5

Answer 20

It's 940 divided by (1 minus 1/5) not (940 divided by 1) minus 1/5 ...

Answer 21

ohh ok

Answer 22

1175?

Answer 23

Yep

Answer 24

so wat do i do now?

Answer 25

Well you have done the second part

Answer 26

The first part would be writing it as \(\displaystyle\Large\sum_{n=1}^\infty 940\times\left(\frac15\right)^{n-1}\)

Answer 27

ok i did that

Answer 28

Then you'd have done everything

Answer 29

the sum is 1,175

Answer 30

yea its the other one the one that u did but the sum is 1,175 thank u so much

Answer 31

the lower limit would be i=0

Answer 32

yea

Answer 33

is there any way u could help me with my last one?

Answer 34

If that's another question please open a new post

Answer 35

ok