math need help
posted by aaron .
study time in X hours
8
5
7
12
10
test grade Y in percent
68
50
62
92
80
a)model the date in a linear function
b)interpret the meaning of the slope

5 , 50
7 , 62
8 , 68
10 , 80
12 , 92
Different :
7  5 = 2
62  50 = 12
12 / 2 = 6
That mean :
y increases for 6 when x increases for 1
That is slope.
Slope intercept equation of straight line :
y = m ( x + x1 ) + y1
In this case :
m = ( y2  y1 ) / ( x2  x1 )
You can take any two points , example:
x1 = 8
y1 = 68
x2 = 10
y2 = 80
m = ( y2  y1 ) / ( x2  x1 )
m = ( 80  68 ) / ( 10  8 ) = 12 / 2 = 6
Slope = 6
y = m ( x  x1 ) + y1
y = 6 ( x  8 ) + 68
y = 6 x  48 + 68
y = 6 x + 20
Proof :
x = 8
y = 6 * 8 + 20 = 48 + 2 = 68
x = 5
y = 6 * 5 + 20 = 30 + 20 = 50
x = 7
y = 6 * 7 + 20 = 42 + 20 = 62
x = 12
y = 6 * 12 + 20 = 72 + 20 = 92
x = 10
y = 6 * 10 + 20 = 60 + 20 = 80 
i need help on my math work