The rate at which a plant grows is constant. At the 3rd week it is 12 inches tall and at the 5th week it is 20 inches tall. If this information is plotted on a coordinate plane, what is the y-coordinate of the the point (1, y)?
A)
1
B)
2
C)
4
D)
9

Question

The rate at which a plant grows is constant. At the 3rd week it is 12 inches tall and at the 5th week it is 20 inches tall. If this information is plotted on a coordinate plane, what is the y-coordinate of the the point (1, y)?
A)
1	
B)
2	
C)
4	
D)
9

p0sitr0n · Answer

they ask you to find the equation of the line and then calculate the y coordinate from it. so the slope m=20-12 / 5-3=8/2=4
so y=4x+b
plug in one of the points, say 3,12
12=4*3+b
b=0
so y=4x, x is time in weeks, y is the height
y=4*1=4
so the answer is c), 4

anonymous · Answer

Thank you very much :)