Question

Phillip lost 25 points on a project for school. He can make changes and receive two-tenths of the missing points back. He can do that 10 times. Create the formula for the sum of this geometric series and explain your steps in solving for the maximum number of points Phillip can earn back.

Can someone please help??? I have been stuck on this question for sooooo long.

Answer 1

@ranga

Answer 2

Pleasseeeeeeee help me understand this.

Answer 3

@welshfella pls pls pls I don't mean to be pushy but I just don't understand this at all.

Answer 4

@inkyvoyd why don't u have a pic so some people know u r here

Answer 5

I don't have a picture for precisely that reason

Answer 6

Can either one of you please help me. I don't need an answer I would just like some guidance.

Answer 7

when i look at the side where the Q is i saw a space there

Answer 8

30

Answer 9

oh geometric series too lazy sorry

Answer 10

yo @snoo help this poor sucker

Answer 11

thats fine thanks anyway

Answer 12

sorry i don't know math.

Answer 13

30

Answer 14

Touka, how do you get 30?

Answer 15

LOL

Answer 16

Oops wrong question sorry lol

Answer 17

Phillip lost 25 points on a project for school. He can make changes and receive two-tenths of the missing points back. He can do that 10 times. Create the formula for the sum of this geometric series and explain your steps in solving for the maximum number of points Phillip can earn back.

Find a_0
find r, the common ratio
next plug and chug into the formula you should already know

Answer 18

ok thank u

Answer 19

I will do my best haha

Answer 20

let me know if you need help with either.

Answer 21

I know the formula is s_n = a_1 - a_1r^n/ 1 - r but I don't understand how to find the common difference or a_0

Answer 22

@inkyvoyd what would a_0 b??

Answer 23

there is no common difference. that is for a arithmetic series. You are dealing with a geometric series with a common RATIO

Answer 24

oh right, hence the r

Answer 25

a_o is the first term in the series. First, we have to come up with what our series is representing. Any ideas?

Answer 26

do you mean whether it is representing an increase or decrease? @inkyvoyd

Answer 27

Im sorry I feel so dumb... I'm not good with these kind of word problems

Answer 28

could you just elaborate on what you mean by representing?

Answer 29

Well, we come up with functions and series to represent certain things in word problems in general. So the question here is, what are we using our series for? what does the series mean? what does it represent?
that is perhaps the second step in a word problem that involves modeling of some sort.
The first is how to model the problem, and that is already given to you (you need to use a geometric series)

Answer 30

it represents the points he can earn back?

Answer 31

Yes. Now what does the initial term in the series probably represent then?

Answer 32

the points he lost right?

Answer 33

so 25

Answer 34

so 25 would be a_1 in the formula?

Answer 35

would the common ration be .2??

Answer 36

Im confused whether 10 or .2 is the common ratio? @inkyvoyd

Answer 37

a_0 is 25 correct

Answer 38

and yes, .2 (two tenths) is the common ratio you are looking for

Answer 39

Ok tell me if I have this right so far: a_0 = 25, r = .2, and n = 10

Answer 40

hmm it has been a while since I have learned how to index the series correctly. Does your formula start at a_0 or a_1? Use what you are given from your formula

Answer 41

a_1 I attached a photo of what it looks like so its more clear

Answer 42

we basically want to find out how many points he can earn pack after making changes 10 times (S_10)? @inkyvoyd

Answer 43

yup

Answer 44

so yeah, start with a_1 (some texts start at a_0 and it changes the numbers of all the formulas by 1 which is why I was asking if you were using a_0 or a_1)

Answer 45

no

Answer 46

shaddy sucks to suck I'm already DONE helping emily here :)

Answer 47

we can go crash anotha question tho

Answer 48

THANK YOU SO MUCh

Answer 49

You have been such a big help you have no idea.

Answer 50

no problem. You have been a big help to my faith in humanity, since you have acted like an intelligent individual capable of reasoning (and doing math) unlike the general majority of this site that prefers to have answers handed out on a plate.
let me know if you need help with anything else
Best wishes to you!

Answer 51

Haha well I really do want to learn and do well! Thank you again for taking the time to help me :)