Upload
others
View
17
Download
0
Embed Size (px)
Citation preview
Statistics and Probability Study Guide: 7th Grade Math
Write each answer on a separate sheet of paper.
Random and unbiased samples:
1.) Mr. Walker wants to learn more about students’ favorite lunch option. Decide whether each method for selecting his sample will be random and unbiased. Explain your answers.
a. Mr. Walker selects 3 students from each homeroom roster, and surveys those students.
b. Mr. Walker selects every student in line A of the cafeteria, and surveys those students.
c. Mr. Walker uses the school directory to select ten students from each grade level.
d. Mr. Walker places a survey in the school newspaper, asking students to complete the survey.
2.) A local reporter is doing a story on the communities’ response to a new Wal-‐Mart being built in the area. Decide whether each conclusion is valid or not, and explain your answer.
a. The reporter surveyed four people at a local gas station, and concluded that the majority of the residents are opposed to the new store.
b. The reporter surveyed every 50th person from the town’s phone directory, and concluded that two times as many people opposed the store, than were in favor of it.
c. The reporter surveyed 100 people at a rally protesting the store, and concluded that all of the residents are against the store being built.
d. The reporter surveyed every third member of the city counsel and concluded that the town is evenly divided.
Measures of Center:
3.) Calculate the mean, median, mode, range, and mean absolute deviation for each set of data.
4.) The tables below shows the amount of rain that two cities received in the given months. Calculate the mean absolute deviation for both sets of data.
City A City B
c. 8, 6, 12, 15, 5, 2
a. -‐5, 7, -‐2, 1, 5, -‐6, -‐2, -‐6
b.
c. -‐185, -‐72, -‐94, -‐73
Month Inches of rain
January 6
February 9
March 11
April 8
May 9
a. Calculate the MAD for both sets of data. What does the MAD tell us about city A and city B?
b. Which cities MAD would be affect more if the month of May was taken out of the data? Explain.
Box-and-whisker plots:
5.) Use the box-‐and-‐whisker plot below to answer the following questions:
6.) Use the box-‐and-‐whisker plot below to decide if each statement is true(t) or false(f).
7.) Use the box-‐and-‐whisker plot below to decide whether Amy or Ed is the answer to the question:
How Likely:
8.) Use the spinner to decide whether each event is: certain, likely, equally likely as not, unlikely, or impossible.
a How much greater is the median salary of Worker A than the median salary of Worker b?
b. What is the inner-‐quartile range for Worker A? Worker B?
c. What percent of Worker B’s weekly earnings fell between $75 and $100? Between $100 and $175?
d. What percent of Worker A’s weekly earnings fell between $100 and $200? Between $125 and $175?
a. Group A’s median is greater than Group B’s median.
b. Group A’s range is greater than Group B’s range.
c. 75% of Group A’s data falls between 76 and 81.
d. 25% of Group B’s data falls between 77 and 80.
e. The inner-‐quartile range is the same for both groups.
a. Who has a greater mean absolute deviation?
b. Who has a greater median?
c. Who has the lower extreme of 76?
d. Who has a greater inner-‐quartile range?
a. Spinning a number less than 3.
b. Spinning a factor of 24.
c. Spinning a number that is both a factor of 12, and a multiple of 3.
d. Spinning a positive number.
e. Spinning a number less than 10.
f. Spinning a number that is a multiple of 2.
g. Spinning a prime number.
Making Predictions
9.) Zack is conducting a survey to learn more about what sports students in his school prefer. Assume that his survey was random and unbiased. Use the data in the table to answer the given questions.
10.) Alaina has a large jar that contains 80 marbles. She took a scoop of 16 marbles from the jar, and recorded their color in the frequency table below. Assume that the sample of 16 marbles was a good representation of the entire jar.
Probability:
11.) Use the spinner below to calculate each probability:
12.) The probability tree shows the possible results from flipping a coin and rolling a dice. Find each probability.
Sport # of students
Basketball 8
Football 14
Soccer 6
Baseball 3
Volleyball 1
Tennis 2
Red Blue Green Yellow Purple
I I I I I I I I I I I I I I I I
The total population of Zack’s school is 850 students, and he surveyed 34 students.
a. How many students in the school would you expect to select basketball as their favorite sport?
b. How many students in the school would you expect to select football as their favorite sport?
c. How many students in the school would you expect to select baseball as their favorite sport?
a. How many red marbles would you expect to find in the entire jar?
b. How many blue or green marbles would you expect to find in the entire jar?
c. How many Yellow marbles would you expect to find in the entire jar?
a. p(even) d. p (8 then 5)
b. p (3 or less) e. p (even then 3)
c. p (prime) f. p (factor of 48)
a. The probability of flipping heads, and rolling a number greater than four.
b. The probability of flipping tails, and rolling a number that is a factor of 12.
c. The probability of flipping heads, and rolling a prime number.
13.) Brenda flipped a coin 3 times. The possible results are shown in the probability tree below. Calculate each probability:
14.) Use the four spinners below to answer the following questions.
15.) You have an ace, ten, queen, king, and jack in your hand. Answer the following questions.
16.) The graph below shows the percent chance that it will rain Thursday through Monday.
a. What is the probability that she will flip at least two heads?
b. What is the probability that se will flip exactly one head, and two tails?
c. What is the probability that she will flip all tails?
d. What is the probability that she will flip at least one heads?
1. 2.
3. 4.
a. If you spin spinner one and spinner two, what is the probability that you will land on a section marked “3” on both spinners?
b. If you spin spinner three and spinner four, what is the probability that you will land on a number less than or equal to 5 on both spinners?
c. If you spin spinners one, two and three, what is the probability that you will land on a number less than 3 on all three of the spinners?
d. If you spin all four spinners, what is the probability that all will land on a number that is at least 2?
a. What is the probability that you randomly select a queen from your hand, put it on the table, then randomly select the jack?
b. What is the probability that you randomly select a ten from your hand, place it back in your hand, then select a ten again?
c. What is the probability that you select a king from your hand, place it on the table, then select the ace from your hand?
a. What is the probability that it will rain on both Thursday and Friday?
b. What is the probability that it will rain on Saturday and Monday?
c. What is the probability that it will rain on all five days?
Answer Key
1.) Mr. Walker wants to learn more about students’ favorite lunch option. Decide whether each method for selecting his sample will be random and unbiased. Explain your answers.
a. Mr. Walker selects 3 students from each homeroom roster, and surveys those students. Yes, this method is random and unbiased. Every student in the school will have an equal chance of being selected, and his sample will be large enough.
b. Mr. Walker selects every student in line A of the cafeteria, and surveys those students. This is not random and unbiased. Line A may serve a specific type of food, and all students may not go thorough line A.
c. Mr. Walker uses the school directory to select ten students from each grade level. Yes, this is a random and unbiased way to select students. Each student is equally likely to be selected.
d. Mr. Walker places a survey in the school newspaper, asking students to complete the survey. This is not unbiased, because not all students read the newspaper, or would repond to the survey.
2.) A local reporter is doing a story on the communities’ response to a new Wal-‐Mart being built in the area. Decide whether each conclusion is valid or not, and explain your answer.
a. The reporter surveyed four people at a local gas station, and concluded that the majority of the residents are opposed to the new store. This is not a valid conclusion, b/c four people is not a large enough sample size.
e. The reporter surveyed every 50th person from the town’s phone directory, and concluded that two times as many people opposed the store, than were in favor of it. This is probably valid if you assume that the majority of people in the town are in the phone directory.
f. The reporter surveyed 100 people at a rally protesting the store, and concluded that all of the residents are against the store being built. This is no valid. Anyone who is at a rally protesting the store, is going to oppose the store.
g. The reporter surveyed every third member of the city counsel and concluded that the town is evenly divided. This is not valid, because only members of city counsel have a chance of being selected.
Measures of Center:
3.) Calculate the mean, median, mode, range, and mean absolute deviation for each set of data.
mean: 8 mean: -‐1 mean: -‐106 median: 7 median: -‐2 median: -‐83 .5 mode: no mode mode: -‐2 and -‐6 mode: no mode range: 13 range: 13 range: 113 MAD: 3⅔ MAD: 4 MAD: 39.5
a. 8, 6, 12, 15, 5, 2
b. -‐5, 7, -‐2, 1, 5, -‐6, -‐2, -‐6
c. -‐185, -‐72, -‐94, -‐73
4.) The tables below shows the amount of rain that two cities received in the given months. Calculate the mean absolute deviation for both sets of data.
City A City B
Box-and-whisker plots:
5. ) Use the box-‐and-‐whisker plot below to answer the following questions:
6.) Use the box-‐and-‐whisker plot below to decide if each statement is true(t) or false(f).
7.) Use the box-‐and-‐whisker plot below to decide whether Amy or Ed is the answer to the question:
Month Inches of rain
January 6
February 9
March 13
April 8
May 9
a How much greater is the median salary of Worker A than the median salary of Worker b? $50
b. What is the inner-‐quartile range for Worker A? Worker B? A: 75 B: 75
c. What percent of Worker B’s weekly earnings fell between $75 and $100? 25% Between $100 and $175? 50%
d. What percent of Worker A’s weekly earnings fell between $100 and $200? 75% Between $125 and $175? 25%
a. Group A’s median is greater than Group B’s median. F
b. Group A’s range is greater than Group B’s range. T
c. 75% of Group A’s data falls between 76 and 81. T
d. 25% of Group B’s data falls between 77 and 80. F
e. The inner-‐quartile range is the same for both groups. T
e. Who has a greater mean absolute deviation? Ed
f. Who has a greater median? Amy
g. Who has the lower extreme of 76? Amy
h. Who has a greater inner-‐quartile range? Ed
a. Calculate the MAD for both sets of data. What does the MAD tell us about city A and city B?
City A: 6.4 City B: 1.28 City B has a smaller MAD, therefore, the data must be less spread out.
b. Which cities MAD would be affect more if the month of May was taken out of the data? Explain.
City A’s data would be affected more, b/c 0 is farther away from the mean than 9.
How Likely:
8.) Use the spinner to decide whether each event is: certain, likely, equally likely as not, unlikely, or impossible.
Making Predictions
9.) Zack is conducting a survey to learn more about what sports students in his school prefer. Assume that his survey was random and unbiased. Use the data in the table to answer the given questions.
10.) Alaina has a large jar that contains 80 marbles. She took a scoop of 16 marbles from the jar, and recorded their color in the frequency table below. Assume that the sample of 16 marbles was a good representation of the entire jar.
Probability:
11.) Use the spinner below to calculate each probability:
Sport # of students
Basketball 8
Football 14
Soccer 6
Baseball 3
Volleyball 1
Tennis 2
Red Blue Green Yellow Purple
I I I I I I I I I I I I I I I I
h. Spinning a number less than 3. unlikely
i. Spinning a factor of 24. likely
j. Spinning a number that is both a factor of 12, and a multiple of 3. unlikely
k. Spinning a positive number. Certain
l. Spinning a number less than 10. likely
m. Spinning a number that is a multiple of 2. equally likely as not
n. Spinning a prime number. unlikely
The total population of Zack’s school is 850 students, and he surveyed 34 students.
a. How many students in the school would you expect to select basketball as their favorite sport? 200
b. How many students in the school would you expect to select football as their favorite sport? 350
c. How many students in the school would you expect to select baseball as their favorite sport? 75
a. How many red marbles would you expect to find in the entire jar? 20
b. How many blue or green marbles would you expect to find in the entire jar? 25
c. How many Yellow marbles would you expect to find in the entire jar? 15
a. p(even) : e as not ½ d. p (8 then 5) 1/ 64 unlikely
b. p (3 or less): 3/8 unlikely e. p (even then 3): 1/16 unlikely
c. p (prime): ½ e as not f. p (factor of 48): ¾ likely
12.) The probability tree shows the possible results from flipping a coin and rolling a dice. Find each probability.
13.) Brenda flipped a coin 3 times. The possible results are shown in the probability tree below. Calculate each probability:
14.) Use the four spinners below to answer the following questions.
a. The probability of flipping heads, and rolling a number greater than four. 1/6
b. The probability of flipping tails, and rolling a number that is a factor of 12. 5/12
c. The probability of flipping heads, and rolling a prime number.
¼
a. What is the probability that she will flip at least two heads? ½
b. What is the probability that se will flip exactly one head, and two tails? 3/8
c. What is the probability that she will flip all tails? 1/8
d. What is the probability that she will flip at least one heads? 7/8
1. 2.
3. 4.
a. If you spin spinner one and spinner two, what is the probability that you will land on a section marked “3” on both spinners? 1/50
b. If you spin spinner three and spinner four, what is the probability that you will land on a number less than or equal to 5 on both spinners? 25/48
c. If you spin spinners one, two and three, what is the probability that you will land on a number less than 3 on all three of the spinners? 1/25
d. If you spin all four spinners, what is the probability that all will land on a number that is at least 2? 7/15
15.) You have an ace, ten, queen, king, and jack in your hand. Answer the following questions.
16.) The graph below shows the percent chance that it will rain Thursday through Monday.
a. What is the probability that you randomly select a queen from your hand, put it on the table, then randomly select the jack? 1/20
b. What is the probability that you randomly select a ten from your hand, place it back in your hand, then select a ten again? 1/25
c. What is the probability that you select a king from your hand, place it on the table, then select the ace from your hand, place it on the table, then select a queen? 1/20
a. What is the probability that it will rain on both Thursday and Friday? 6%
b. What is the probability that it will rain on Saturday and Monday? 16%
c. What is the probability that it will rain on all five days?
0.384%