STAY COOL Final Quiz: Grade 9

1.

Chantelle won 9 of 15 tennis games she played. At this rate, which of the following is the best prediction of the number of tennis games she will win out of her next 12 games?

A.

4
B.

7
C.

11
D.

6

Correct Answer
B. 7

Explanation
Based on the given information, Chantelle won 9 out of 15 tennis games she played. This can be simplified to a fraction, where she won 9/15 of her games. To find the best prediction for the number of games she will win out of her next 12 games, we can set up a proportion. Since 9/15 is equivalent to 3/5, we can say that 3/5 is the fraction of games she won. Setting up the proportion, we have 3/5 = x/12, where x represents the number of games she will win out of the next 12. Cross multiplying, we get 5x = 36, and solving for x, we find that x is approximately 7. Therefore, the best prediction is that Chantelle will win 7 out of her next 12 games.

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2.

Millie entered her dog in a dog show. Her dog got a score of 64. Which measure of data can Millie use to determine whether her dog’s score was in the top half of all scores at the show?

A.

Median
B.

Mode
C.

Mean
D.

Range

Correct Answer
A. Median

Explanation
Millie can use the median to determine whether her dog's score was in the top half of all scores at the show. The median is the middle value when the scores are arranged in ascending order. If her dog's score is greater than or equal to the median, it means that her dog's score is in the top half of all scores.

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3.

Dante has 5 times as many marbles as Kenny. Juan has 1/3 as many marbles as Dante. If Kenny has 30 marbles, how many marbles does Juan have?

A.

6
B.

50
C.

2
D.

18

Correct Answer
B. 50

Explanation
If Kenny has 30 marbles, then Dante has 5 times as many, which is 150 marbles. Juan has 1/3 as many marbles as Dante, so Juan has 1/3 * 150 = 50 marbles. Therefore, the correct answer is 50.

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4.

Josh earns money by washing cars in his neighborhood. He spent $215 on supplies and charges $15 for each car washed. Josh’s profit, p, can be represented by the functionp = 15n − 215, where n represents the number of cars that Josh washes. What is the minimum number of cars Josh must wash to make a profit?

A.

14
B.

29
C.

15
D.

Not here

Correct Answer
C. 15

Explanation
To find the minimum number of cars Josh must wash to make a profit, we need to determine when the profit function p = 15n - 215 becomes positive. Since p represents profit, it needs to be greater than 0. Setting the equation equal to 0 and solving for n, we get 15n - 215 > 0. Simplifying the inequality, we find n > 215/15. Dividing 215 by 15, we get approximately 14.33. Since n represents the number of cars, it must be a whole number. Therefore, the minimum number of cars Josh must wash to make a profit is 15.

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5.

Which expression is equivalent to −7(x − 2) + 5(3 − x) − 4x?

A.

−16x + 1
B.

−16x + 29
C.

−2x + 1
D.

−12x + 13

Correct Answer
B. −16x + 29

Explanation
The given expression can be simplified by distributing the coefficients. Distributing the coefficients, we get: -7x + 14 + 15 - 5x - 4x. Combining like terms, we get: -16x + 29. Therefore, the expression is equivalent to -16x + 29.

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6.

A salesperson’s commission, c, is 6% of her total sales, s. Which function best represents the salesperson’s commission?

A.

C = 0.06s
B.

C = s + 0.06
C.

C = s + 0.06s
D.

C = ( 6 / s )(100)

Correct Answer
A. C = 0.06s

Explanation
The function c = 0.06s represents the salesperson's commission because it states that the commission (c) is equal to 6% (0.06) of the total sales (s). This aligns with the given information that the commission is 6% of the total sales.

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7.

If today is Tuesday, what day of the week will it be 100 days from today?

A.

Tuesday
B.

Wednesday
C.

Thursday
D.

Friday

Correct Answer
C. Thursday

Explanation
If today is Tuesday, and we add 100 days to it, we will reach Thursday. This is because there are 7 days in a week, so every 7 days the day of the week repeats. Adding 100 days to Tuesday means we have 14 complete weeks and 2 extra days. Therefore, the day 100 days from today will be Thursday.

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8.

If the diameter of a circle is dilated by a scale factor of 0.6, what will be the effect on the circle’s circumference?

A.

The circumference will be 0.3 times as large.
B.

The circumference will be 0.36 times as large.
C.

The circumference will be 1.88 times as large.
D.

The circumference will be 0.6 times as large.

Correct Answer
D. The circumference will be 0.6 times as large.

Explanation
When a circle is dilated, both the radius and the diameter are multiplied by the scale factor. In this case, the diameter is dilated by a scale factor of 0.6. Since the circumference of a circle is directly proportional to its diameter, when the diameter is reduced to 0.6 times its original size, the circumference will also be reduced to 0.6 times its original size. Therefore, the correct answer is that the circumference will be 0.6 times as large.

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9.

Point S and point T are located on the same coordinate plane. Both the x-coordinate and the y-coordinate for point S are negative. Both the x-coordinate and the y-coordinate for point T are positive. Which statement about the line containing points S and T must be true?

A.

The graph of the line has a negative slope.
B.

The graph of the line has a positive slope.
C.

The graph of the line has a negative y-intercept.
D.

The graph of the line has a positive y-intercept.

Correct Answer
B. The graph of the line has a positive slope.

Explanation
Since point S has negative x and y coordinates, and point T has positive x and y coordinates, it means that as you move from S to T on the line, the values of both x and y are increasing. This indicates a positive slope, as the line is moving upward from left to right. Therefore, the statement "The graph of the line has a positive slope" is true.

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10.

Mr. Sylvester bought gardening supplies for $79.75, not including tax. If the tax rate was 8%, what was the total cost of these gardening supplies, including tax?

A.

$86.13
B.

$73.37
C.

$87.75
D.

Not here

Correct Answer
A. $86.13

Explanation
The total cost of the gardening supplies, including tax, can be calculated by adding the tax amount to the original cost. To find the tax amount, we multiply the original cost ($79.75) by the tax rate (8%). 8% of $79.75 is $6.38. Adding this tax amount to the original cost gives us a total cost of $86.13.

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11.

Desmond wants to take guitar lessons. The one-time registration fee is $60, and each lesson costs $40. Which of the following inequalities can Desmond use to determine x, the number of lessons he can take if he wants to spend no more than c dollars?

A.

60x + 40x ≤ c
B.

60 + 40x ≤ c
C.

60x + 40x ≥ c
D.

60 + 40x ≥ c

Correct Answer
B. 60 + 40x ≤ c

Explanation
The correct answer is 60 + 40x ≤ c because this inequality represents the total cost of the registration fee ($60) added to the cost of each lesson ($40) multiplied by the number of lessons (x), which should be less than or equal to the amount Desmond wants to spend (c dollars).

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12.

David wants to spread wildflower seeds in a rectangular field that is 60 feet wide and 70 feet long. Each package of wildflower seeds covers about 175 square feet and costs $6.95. Which of the following amounts is closest to the total cost of the wildflower seeds David needs for this field?

A.

$24.00
B.

$170.00
C.

$604.00
D.

$310.00

Correct Answer
B. $170.00

Explanation
To find the total cost of the wildflower seeds, we need to calculate the area of the rectangular field. The area can be found by multiplying the width (60 feet) by the length (70 feet), which gives us 4200 square feet. Since each package of wildflower seeds covers 175 square feet, we divide the total area by 175 to determine the number of packages needed. 4200 divided by 175 is 24. Therefore, the total cost of the wildflower seeds is 24 packages multiplied by $6.95, which equals $166.80. The closest amount to this is $170.00.

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Stay Cool Final Quiz: Grade 9

Chantelle won 9 of 15 tennis games she played. At this rate, which of the following is the best prediction of the number of tennis games she will win out of her next 12 games?

Millie entered her dog in a dog show. Her dog got a score of 64. Which measure of data can Millie use to determine whether her dog’s score was in the top half of all scores at the show?

Dante has 5 times as many marbles as Kenny. Juan has 1/3 as many marbles as Dante. If Kenny has 30 marbles, how many marbles does Juan have?

Which expression is equivalent to −7(x − 2) + 5(3 − x) − 4x?

A salesperson’s commission, c, is 6% of her total sales, s. Which function best represents the salesperson’s commission?

If today is Tuesday, what day of the week will it be 100 days from today?

If the diameter of a circle is dilated by a scale factor of 0.6, what will be the effect on the circle’s circumference?

Point S and point T are located on the same coordinate plane. Both the x-coordinate and the y-coordinate for point S are negative. Both the x-coordinate and the y-coordinate for point T are positive. Which statement about the line containing points S and T must be true?

Mr. Sylvester bought gardening supplies for $79.75, not including tax. If the tax rate was 8%, what was the total cost of these gardening supplies, including tax?

Desmond wants to take guitar lessons. The one-time registration fee is $60, and each lesson costs $40. Which of the following inequalities can Desmond use to determine x, the number of lessons he can take if he wants to spend no more than c dollars?

David wants to spread wildflower seeds in a rectangular field that is 60 feet wide and 70 feet long. Each package of wildflower seeds covers about 175 square feet and costs $6.95. Which of the following amounts is closest to the total cost of the wildflower seeds David needs for this field?