Question

Phillip received 75 points on a project for school. He can make changes and receive two-tenths of the missing points back. He can do this 10 times. Create the formula for the sum of this geometric series, and explain your steps in solving for the maximum grade Phillip can receive.

Answer 1

@undeadknight26

Answer 2

@mathmath333

Answer 3

is the total number of points on a project is \(100.\) ?

Answer 4

Im assuming so and I have to find the maximum he can make if he change things

Answer 5

this is worded bad

Answer 6

hmm thought it was 100 myself as well
though it's really unclear it's 100
the only clear part is that

whatever amount was previous
making changes gives him the next term, which is 2/10 of the total

and that he can do that 10 times only

may not amount to 100 though

Answer 7

hint: \(\begin{array}{cccccclllllll}
term&&a_1&a_2&a_3&...
\\\hline\\
value&&75&75+\frac{2}{10}\ of \ {\color{purple}{ 75}}& \left( 75+\frac{2}{10}\textit{of 75}\right)+\frac{2}{10}\ of {\color{purple}{ \left( 75+\frac{2}{10}\textit{of 75}\right) }}&...
\end{array}\)

Answer 8

hmmm

Answer 9

okay. it says create the formula so...

Answer 10

actually "the missing points back" are not 25...
so .... hmm

Answer 11

are not 75 rather

Answer 12

this value is large

http://www.wolframalpha.com/input/?i=75%5Cfrac%7B1-%2875*2%2F10%29%5E%2810%29%29%7D%7B1-75*2%2F10%7D%3D

Answer 13

so if we assume is 100
he's got 75 already
the "missing points" are 25

so each change makes up for 2/10 of that

Answer 14

okay. do i use this Sn =(1-r^n)/1-r formula?

Answer 15

the formula is correct, but the values we are assuming should be correct.

Answer 16

im confused now. Like where are we

Answer 17

for instance the value this is giving is in million
http://www.wolframalpha.com/input/?i=75*%5Cfrac%7B1-%2825*2%2F10%29%5E%2810%29%29%7D%7B1-25*2%2F10%7D%3D

Answer 18

hmmm I read it as \(\large \begin{array}{lllllll}

\begin{array}{llll}
term\\changes
\end{array}&value
\\\hline\\
a_1&75\\
a_2&75+\frac{2}{10}\ of \ {\color{purple}{ 25}}\\
a_3&75+\frac{4}{10}\ of \ {\color{purple}{ 25}}\\
a_4&75+\frac{6}{10}\ of \ {\color{purple}{ 25}}\\
a_5&75+\frac{8}{10}\ of \ {\color{purple}{ 25}}\\
a_6&75+\frac{10}{10}\ of \ {\color{purple}{ 25}}\\
a_7&75+\frac{11}{10}\ of \ {\color{purple}{ 25}}\\
...&...
\end{array}\)

Answer 19

but thats not geometric series right

Answer 20

thats not

Answer 21

ive been trying to do this for an hour

Answer 22

the question says to create the formula and it doesn't specifically asking the value

Answer 23

but i don't know what to write

Answer 24

may be just write this ,not sure though.

\(\large \color{black}{\begin{align} \sum_{i=1}^{10}\text{nth term}\hspace{.33em}\\~\\
\end{align}}\)

Answer 25

idk thank for trying