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Mathematics 21 Online
OpenStudy (freemap):

The table shows the approximate population of a city, in thousands, for the years 2009–2013. Which is the best prediction for the city’s approximate population in 2030? A. 153,000 B. 167,000 C. 182,000 D. 195,000

OpenStudy (freemap):

Vocaloid (vocaloid):

well, I would treat years as the x variable and population as the y variable, then write an equation using two points from the table I'll pick the first and last point (2009,78) and (2013,93) then write an equation in y = mx + b form

OpenStudy (freemap):

OK, about to it work out

OpenStudy (freemap):

I got 1920 and -1936 and when I didvided got -1.00833so on. I don't think I did it right

Vocaloid (vocaloid):

remember, slope = (y2-y1)/(x2-x1) (93-78) = ?

OpenStudy (freemap):

I was doing 93-73 okay I'm about to do it all over

OpenStudy (freemap):

I mean I was doing 93 minus 2013 okay about to work it all out again

OpenStudy (freemap):

okay I got 3.75 for slope, than I have to work out to get y intercept

OpenStudy (freemap):

ok my slope is 3.75, then I said y-y1=m(x-x1) so it was y-78=3.75-2009 which i got + 78 to -2009= 1931

OpenStudy (freemap):

I'm kinda lost now

OpenStudy (freemap):

wait I think I figured it out and got 2029

Vocaloid (vocaloid):

ah, I think you've mixed up the equation a bit, let me lend you a hand ^ ^ y-78 = 3.75(x-2009) start by distributing the 3.75

OpenStudy (freemap):

y-78=3.75x-7533.75 y-78+78=3.75x +78-7533.75 y=3.75x-7455.75 3.75x/-7455.75

Vocaloid (vocaloid):

you can stop here y=3.75x-7455.75 this is the equation we need, now plug in x = 2030

OpenStudy (freemap):

ok so 3.75 times 2030. if so that =7612.5

Vocaloid (vocaloid):

uh, not quite... we're looking for the value of y 3.75*(2030) - 7455.75

Vocaloid (vocaloid):

= ?

OpenStudy (freemap):

2030-7455.75

OpenStudy (freemap):

I meant 7612.5-7455.75

Vocaloid (vocaloid):

ok, now subtract those two values

OpenStudy (freemap):

156.75

Vocaloid (vocaloid):

good, now we multiply by 1000 to get 156,750 which means that A is the answer that best approximates the population in 2030

OpenStudy (freemap):

Thanks, I don't know to say. You've always been there to help me. Thanks

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