1. Week #23 Bell Ringers & Quiz
8th grade math

2. Bell Ringer Monday Figure A is dilated to create Figure B. A B
What type of dilation occurred?
Calculate the scale factor.
Calculate the original volume.
Calculate the new volume.
How is the volume affected?
3 in
2 in
1 in
1.5 in
4 in
6 in 2

3. Figure A is dilated to create Figure B. A B
What type of dilation occurred?
Calculate the scale factor.
3 in
2 in
1 in
1.5 in
4 in
6 in
Enlargement

4. Figure A is dilated to create Figure B. A B
Calculate the original volume.
4. Calculate the new volume.
3 in
2 in
1 in
1.5 in
4 in
6 in

5. Figure A is dilated to create Figure B.
A B
5. How is the volume affected?
3 in
2 in
1 in
1.5 in
4 in
6 in
Say NO to Oreos!
The new volume is 3 3/8 times larger than the original volume.

6. Calculate the scale factor used to dilate the triangle.
Quiz Monday
Calculate the scale factor used to dilate the triangle. 6

7. What is the scale factor?
Calculate the scale factor used to dilate the triangle.
Triangle ABC
Enlargement
AB= 14 cm
BC= 12 cm
A’C’= 21 cm
B’C’= 18 cm
What is the scale factor?
To find the scale factor, I divided the new dimension by the original dimension. Since, the new dimensions are larger, an enlargement occurred. Since it is an enlargement, the scale factor should be greater than 1.
The scale factor is 1.5. 7

8. Bell Ringer Tuesday 4 ft 9 ft
Calculate the amount of fencing needed for the rectangular pen.
Calculate the amount of fencing needed for the circular water trough.
Calculate the square footage of grass.

9. Calculate the amount of fencing needed for the rectangular pen.
2 ft
4 ft
9 ft
Calculate the amount of fencing needed for the rectangular pen.
P =
P =
P = 26 ft

10. C = 2πr C = 2 (3.14) (2) C = (6.28) (2) C = 12.56 ft
2. Calculate the amount of fencing needed for the circular water trough.
C = 2πr
C = 2 (3.14) (2)
C = (6.28) (2)
C = ft

11. 3. Calculate the square footage of grass. .
2 ft
4 ft
9 ft
3. Calculate the square footage of grass. .
A rect. = lw
A = 4(9)
A = 36 ft2
Area Shaded:
36 – 12.56
23.44 ft2
A circle = πr2
A = (3.14) (22)
A = ft2

12. Quiz Tuesday
At an auto parts factory, Audrey can press an average of 16 gears in 30 minutes. At this rate, how many hours will it take for her to press 400 gears? 12

13. How long will it take? It will take 12.5 hours to press 400 gears.
At an auto parts factory, Audrey can press an average of 16 gears in 30 minutes. At this rate, how many hours will it take for her to press 400 gears?
How long will it take?
16 gears in 30 minutes
400 gears
hours
To find the number of minutes it will take to press 400 gears, I set up a proportion. I multiplied by a scale factor of 25. I divided the number of minutes by 60 to convert to hours.
It will take 12.5 hours to press 400 gears. 13

14. Bell Ringer Wednesday
Jackie built a fence around her garden to keep animals out. The dimensions of the area enclosed by the fence are shown in the diagram.
1. How many feet of fencing was needed?
2. Calculate the number of square feet enclosed by the fence. 14

15. Jackie built a fence around her garden to keep animals out
Jackie built a fence around her garden to keep animals out. The dimensions of the area enclosed by the fence are shown in the diagram.
1. How many feet of fencing was needed?
6ft
6ft
8.5ft
15 - 9=6ft
=6ft 15

16. Jackie built a fence around her garden to keep animals out
Jackie built a fence around her garden to keep animals out. The dimensions of the area enclosed by the fence are shown in the diagram.
2. Calculate the number of square feet enclosed by the fence.
6ft
18 ft2
6ft
180 ft2 16

17. Quiz Wednesday
The isosceles trapezoids are similar. What is the length in centimeters of each base of the isosceles trapezoid PQRS?
A. b1 = 7
b2 = 10
B. b1 = 4
C. b1 = 6
b2 = 8
D. b1 = 9
b2 = 18 17

18. What is the length of each base?
The isosceles trapezoids are similar. What is the length in centimeters of each base of isosceles trapezoid PQRS?
Similar trapezoids
KL = 9 cm
NM = 12 cm
LM = 6 cm
PS = 4 cm
What is the length of each base?
I found the scale factor used by dividing the new side by the original side. I multiplied both bases by the scale factor to get the new dimensions of trapezoid PQRS.
The length of the bases are 6 cm and 8 cm. 18

19. Bell Ringer Thursday
During a sale Sasha paid $25.00 for a pair of shoes that had a regular price of $ What was the percent discount on the pair of shoes?
2. A sequence of numbers was generated using the rule 3n − 2, where n represents a number’s position in the sequence. Write the first four terms of the sequence. 19

20. 1. During a sale Sasha paid $25
1. During a sale Sasha paid $25.00 for a pair of shoes that had a regular price of $ What was the percent discount on the pair of shoes? 20

21. 2. A sequence of numbers was generated using the rule 3n − 2, where n represents a number’s position in the sequence. Write the first four terms of the sequence. 1 2 3 4
nth
3n-2 1 4 7 10 21

22. Quiz Thursday
Nadia bought 7 lawn chairs that cost $9.49 each. The tax rate was 8.25%. Which equation can be used to find c, the total cost of the chairs, including tax?
A c = 7(9.49)(0.0825) B c = 7(9.49) C c = 7(9.49)(0.0825) D c = 7(9.49) + 7(9.49)(0.0825) 22

23. Which equation can be used?
Nadia bought 7 lawn chairs that cost $9.49 each. The tax rate was 8.25%. Which equation can be used to find c, the total cost of the chairs, including tax?
7 chairs
$9.49 each
8.25% tax
Which equation can be used?
I wrote down what I would do to solve the problem. I need to find the total cost of the chairs by multiplying the number of chairs by the chair cost. To find the tax, I multiply the chair cost by the tax rate (converted to a decimal). I add the tax to the chair cost for the total cost.
Equation D can be used. 23

24. 1. How many square feet of material is needed to make the tent?
Bell Ringer Friday
1. How many square feet of material is needed to make the tent?
2. How much ground space do we need to put up the tent?
8.1 ft
8.1 ft
7 ft
16 ft
12 ft 24

25. 1. How many square feet of material is needed to make the tent?
8.1 ft
8.1 ft
7 ft
16 ft
12 ft 25 25

26. 2. How much ground space do we need to put up the tent?
8.1 ft
8.1 ft
7 ft
16 ft
12 ft 26 26

27. Canoe rentals are as follows: 6 hours: $30.00 1 hour: $7.00
Quiz Friday
Canoe rentals are as follows:
6 hours: $30.00
1 hour: $7.00
You are planning a 5 hour canoe trip. Which rental will give you the best rate? 27

28. Which rental is cheaper?
Canoe rentals are as follows:6 hours: $30.00; 1 hour: $7.00
You are planning a 5 hour canoe trip. Which rental will give you the best rate?
6 hours = $30
1 hour = $7
5 hour rental
Which rental is cheaper?
To find the unit rate, I divided the rental price by the number of hours. I multiplied by a scale factor of 1/6. For $30, it is $5 per hour. This is $2 cheaper than renting it for $7 per hour.
The $30 for 6 hours rental is the cheapest. 28