Free STAAR Grade 8 Mathematics Practice Questions
1. Adrian measures the circumference of a circular picture frame, with a radius of 3 inches. Which of the following is the best estimate for the circumference of the frame?
- 12 inches
- 16 inches
- 18 inches
- 24 inches
2. A pentagon with side lengths of 9 cm, 18 cm, 24 cm, 18 cm, and 9 cm is dilated by a scale factor of 1/3. Which of the following represents the dimensions of the dilated pentagon?
- 3 cm, 9 cm, 8 cm, 9 cm, 3 cm
- 6 cm, 3 cm, 12 cm, 6 cm, 3 cm
- 3 cm, 6 cm, 8 cm, 6 cm, 3 cm
- 6 cm, 18 cm, 9 cm, 6 cm, 9 cm
3. A rectangle has a width of 9 inches and a length of 15 inches. If the rectangle is enlarged by a scale factor of 3/2, what is the perimeter of the dilated rectangle?
- 68 inches
- 72 inches
- 60 inches
- 64 inches
4. Hannah's parents open a savings account for her, with an initial deposit of $245. They deposit $125 per month into her account. Without considering interest earned, how much money will be in Hannah's account after 5 years?
5. Brian designs a cylindrical container. He wishes to paint only the lateral face. If the cylinder has a radius of 6 inches and a height of 8 inches, how many square inches of the container will he paint?
- 48π inches2
- 96π inches2
- 108π inches2
- 144π inches2
6. A cylinder has a height of 9 inches and a radius of 4 inches. If the height remains the same, but the radius increases by 8 inches, what is the effect on the volume of the cylinder?
- He's worried that he'll fall
- He's worried the crane won't really take him to the pond
- He's friends with the crane
- He's glad to go with the crane
7. Yin wishes to track the number of new clients she has secured each year. Which of the following representations is most appropriate for displaying this data?
- Line plot
- Circle graph
- Line graph
- Stem-and-leaf plot
8. Monique rolls a die and spins a spinner, with six equally spaced sections, labeled 1 - 6. What is the probability she rolls a number less than 4 or the spinner lands on 2?
9. Marcele purchases a television as a gift to her husband. She needs to wrap the box, containing the television. If the box has dimensions of 22 inches by 19 inches by 17 inches, how many square inches of wrapping paper will she need?
10. The side lengths of a square are increased by a factor of 6. Which of the following correctly describes the effect on the area?
- The area is increased by 36
- The area is 12 times larger
- The area is 36 times larger
- The area is increased by 12
Grade 8 Mathematics Answer Key
1. Answer: C
The circumference of a circle can be found by using the formula, C=πd. Since the radius is equal to 3 inches, the diameter is equal to 6 inches. Substituting a value of 6 inches for d and estimating pi to be 3, gives an approximate circumference of 18 inches.
2. Answer: C
Dilation of the pentagon by a scale factor of one-third indicates that each dimension of the dilated figure will be one-third that of the dimension in the original figure. Thus, the measurements of the dilated figure can be written as: 9*1/3 cm, or 3 cm; 18*1/3 cm, or 6 cm; 24*1/3 cm, or 8 cm; 18*1/3cm, or 6 cm; and 9*1/3 cm, or 3 cm.
3. Answer: B
The width of the enlarged rectangle is equal to the product of 9 in and 3/2 , or 13.5 in. The length of the enlarged rectangle is equal to the product of 15 in and 3/2, or 22.5 in. Thus, the perimeter is equal to the sum of 13.5 in, 13.5 in, 22.5 in, and 22.5 in, or 72 in.
4. Answer: C
The initial deposit of $245 represents the constant amount, or y-intercept. The recurring deposits of $125 per month represent the slope of the variable amount. Thus, the equation, y=125x+245, can be used to find the amount in savings, after x months. Five years equals 60 months, and substitution of 60 for the variable, x, gives: y=125(60)+245, or 7,745. Thus, Hannah will have $7,745 in her account after 5 years.
5. Answer: B
The area of the lateral face of a cylinder is calculated by using the expression, 2πrh, where r represents the radius and h represents the height. Substitution of the radius of 6 inches and height of 8 inches into the formula gives: 2π(6)(8), or 96π. Thus, he will paint 96π square inches.
6. Answer: B
A cylinder with a height of 9 inches and radius of 4 inches has a volume equal to π(4)2 (9) cubic inches, or approximately 452.16 cubic inches. A cylinder with a height of 9 inches and a radius of 12 inches has a volume equal to π(12)2 (9) cubic inches, or approximately 4,069.44 cubic inches. The volume of the second cylinder is 9 times larger than the volume of the original cylinder.
7. Answer: C
A line graph can be used to track data over a period of time.
8. Answer: D
The probability of independent events, A or B, can be found, by using the formula, P(A or B)=P(A)+P(B). Thus, the probability can be written as 3/6+1/6, or 4/6, which reduces to 2/3.
9. Answer: C
The amount of wrapping paper she will need is equal to the surface area of the box. The surface area of a rectangular prism can be determined by using the formula: SA=2(lw)+2(lh)=2(wh). Substituting the given dimensions allows you to write: SA=2(22*19)+2(22*17)+2(19*17), which equals 2,230. Thus, she will need 2,230 square inches of wrapping paper.
10. Answer: C
A square with side length, a, has an area equal to s2. A square with side length of 6a has an area equal to 36a2. Thus, the area of the second square is 36 times larger.
by Enoch Morrison
Last Updated: 12/14/2017