Answer:
C
Step-by-step explanation:
y = mx + c
m = (y2 - y1 )/ (x2 - x1)
using (1 , 7) & (2,5)
y2 = 5 y1 = 7 so y2 -y1 = -2
x2 = 2 x1 = 1 so x2 - x1 = 1
m - -2/1 = -2
y = -2x + c
when x =1 y = 7
so 7 = -2 + c
=> c =9
y = -2x + 9
if ordered pairs (2, 5) and (4, 1) used
m = (1-5)/(4-2)
=> m = -4/2
=> m = -2
y = -2x + c
for x =2 y =5
5 = -2*2 + c
=> c = 9
y = -2x + 9
she would have got same equation
1. You already did it.
2. Table
3. t (years since 1990)
4. n (# of cigarettes sold)
5. (t, n)
6. You can see the distribution of the data pretty neatly. There are also many more advantages including it's easier to calculate standard deviation, easier to see the mean, mode and median, and it's also much easier to just tell the extrema of the dataset by just looking at the scattergram.
