Grade 8 Scatter Plots Worksheets

How to solve Grade 8 scatter plots problems

Real problems from these worksheets, solved one step at a time — the same explanations your child sees when practicing online.

1. Example 1

   x = x · y = y

   Data: x (x) and y (y)

   x	1	3	5	7
   y	54	51	38	29
   x	9	11	13	15
   y	23	20	21	12

   What type of association does the scatter plot show between the x-values and the y-values?

   1. Read the points from left to right (x from 1 to 15). Their y-values are 54, 51, 38, 29, 23, 20, 21, 12.
   2. Overall they go down: from 54 on the left to 12 on the right. As x increases, y tends to decrease.
   3. When both go in opposite directions, the association is negative.

   Answer: negative

2. Example 2

   x = Temperature (°F) · y = Cones sold

   Data: Temperature (°F) (x) and Cones sold (y)

   x	64	68	72	76
   y	125	135	157	167
   x	80	84	88	92
   y	183	205	215	237

   The line of best fit is y = 4x − 134. Is the point (80, 183) above or below the line?

   1. Find the line's y-value at x = 80: y = 4 × 80 − 134 = 320 − 134 = 186.
   2. The point's y-value is 183, which is less than 186.
   3. So the point (80, 183) is below the line.

   Answer: below

3. Example 3

   x = Temperature (°F) · y = Cones sold

   Data: Temperature (°F) (x) and Cones sold (y)

   x	60	64	68	72
   y	34	39	50	69
   x	76	80	84	88
   y	81	86	99	118

   How many points show a number of cones sold greater than 92?

   1. List the y-value of each of the 8 points: 34, 39, 50, 69, 81, 86, 99, 118.
   2. Greater than 92: 99, 118 (not 34, 39, 50, 69, 81, 86).
   3. Count them: 2 points.

   Answer: 2