Question

Two ocean beaches are being affected by erosion. The table shows the width, in feet, of each beach at high tide measured where 1995 is represented by year 0.

Answer 1

Describe the patterns shown by the erosion data measurements shown for each of the beaches in the table.
Between which years will the beaches have approximately the same width?
Assuming these rates remain constant, what can you do to get a better approximation of when the two beaches will have the same width?

Answer 2

Year number Western Beach width (in feet) Dunes Beach width (in feet)
0 100 20
5 90 45
10 80 70
11 78 75
12 76 80
15 70 95

Answer 3

@peachpi please helppp

Answer 4

Western Beach is losing sand, Dunes beach is gaining sand.

Between 11 and 12 years

Plot the data against time and draw a curve that goes through the data. Where the two lines cross is the time when both beaches are the same width.

Answer 5

ok i think you are correct does anyone agree with him.

Answer 6

I don't need to get anything wrong

Answer 7

@CBARREDO1 is correct

Answer 8

ok thanks

Answer 9

You are such a great person I always count on you to help me with me with math @peachpi thanks a lot.

Answer 10

You're welcome. Thank you! I appreciate that :)

Answer 11

I feel left out here ;-;

Answer 12

and thanks to you as well c

Answer 13

so @CBARREDO1 is this your paper or did you just do this tooday

Answer 14

because i don't want to copy

Answer 15

@CBARREDO1 don't feel left out. you did all the hard work! :)

Answer 16

yea definitely i just messaged him

Answer 17

what paper are you talking about?

Answer 18

the problem response you gave me

Answer 19

No, I just analyzed, where could I copy it from xD?

Answer 20

@CBARREDO1 how would i graph this on geogbra

Answer 21

any one knows

Answer 22

What's geogbra?

Answer 23

ldo you know what is desmos

Answer 24

@peachpi do you know how to graph on geogbra

Answer 25

or desmos

Answer 26

I know desmos

Answer 27

ok how on desmos. i don't know hot to graph point only equations

Answer 28

sorry I don't know geobra. I don't really know how to do points on desmos.

Answer 29

cant be mad cause i don't know either.

Answer 30

you can make equations for the lines by hand or use wolframalpha to get the line between points. then graph the lines on desmos

Answer 31

ok let me see

Answer 32

im on the website and i dont know where to go

Answer 33

Go to wolframalpha.com
There should be a box to type in.
Enter this to get an equation for the first beach: line through (0,100) and (5,90)

Answer 34

k

Answer 35

it says y=100-2x

Answer 36

well is their another 2 point to do?

Answer 37

put that equation in desmos, and then the line comes do the same for the next

Answer 38

^yep

Answer 39

wait but aren't we trying to figure out the approx for year 11 and 12

Answer 40

when they will be the same width

Answer 41

approximation of when the two beaches will have the same width?

Answer 42

that's why you're graphing them. once you have the lines graphed you're looking for the intersection point, which will be between 11 and 12

Answer 43

but 0,100 is is year 0 while 5,90 is year 5. Year 11 and 12 are the closest, so should't we be doing year 11 and 12 then finding where intersection point is?

Answer 44

and how will we have two lines

Answer 45

please talk back

Answer 46

@peachpi WHAT HAPPENED

Answer 47

sorry didn't realize you had posted something here. You're going to have 2 different equations, one for each beach. We found the first equation is y = 100 - 2x.

Find the second one using 2 points from the other beach, like (0, 20) and (5,45).

As far as choosing 11 and 12, it doesn't matter. It takes 2 points to define a line, it doesn't matter which two points you use. You can use the points that correspond to 11 and 12 and the results will be the same. I just picked the two I chose because they were the top two points.

Answer 48

I COPY AND PASTED JUST AS IT IS HERE SO IT IS Y=5X+20 sorry about caps

Answer 49

ok. so the two lines you're going to graph are y = 5x + 20 and y = 100-2x

Answer 50

and you're looking for the intersection point

Answer 51

it is (11.43,77.14)

Answer 52

yes

Answer 53

ok thank you

Answer 54

youre welcome