A
What is the definition of a categorical variable?
Categorical variables place the person or thing into a category.
Round 3.864 to the nearest tenth.
3.9
What is the definition of population?
The population in a statistical study is the entire group of individuals about which we want information.
What is the formula for IQR?
IQR = Q3-Q1
What is the definition of sampling?
A sample is a part of the population from which we actually collect information. We use a sample to draw conclusions about the entire population.
Express the following percentage as a decimal:
1%
1 % = 1/100 = 0.01
Positive or negative correlation?
When an employee works more hours, their paycheck also increases.
Positive
Express the following percentage into a fraction in the lowest terms: 48%
48 % = 48/100 = 12/25
For any event A, 𝑷(A does not occur) = 𝟏 − 𝑷(𝑨)
Find the mean of {5, 15, 25, 10, 15}
14
True or False:
Mean > Median if it is right skewed
True
On a six-sided die, each side has a number between 1 and 6. What is the probability of throwing a 3 or a 4?
On a six-sided die, the probability of throwing any number is 1 in 6. The probability of throwing a 3 or a 4 is double that, or 2 in 6. This can be simplified by dividing both 2 and 6 by 2.
Therefore, the probability of throwing either a 3 or 4 is 1 in 3.
What is the median?
1; 1; 2; 2; 4; 6; 6.8; 7.2; 8; 8.3; 9; 10; 10; 11.5
(6.8 + 7.2)/2 = 7
What is the definition of a sample? What does it mean if the sample is biased?
A sample is a part of the population from which we actually collect information. We use a sample to draw conclusions about the entire population. The design of a statistical study is biased if it systematically favors certain outcomes.
What is the definition of undercoverage?
Undercoverage occurs when some groups in the population are left out of the process of choosing the sample.
Define simple random sample (SRS)
A simple random sample (SRS) of size n consists of n individuals from the population chosen in such a way that every set of n individuals has an equal chance to be the sample actually selected.
Make a histogram of this data.
Cholesterol of Men (x): 0-199, 200-399, 400-599, 600-799, 800-999, 1000-1199, 1200-1399
Frequency (y): 13, 11, 5, 8, 2, 0, 1
Draw on poster board.
There are 6 blue marbles, 3 red marbles, and 5 yellow marbles in a bag. What is the probability of selecting a blue or red marble on the first draw?
There are 6 blue marbles and 3 red marbles for a total of 9 desired outcomes. Add the total number of marbles to get the total number of possible outcomes, 14. The probability that a red or blue marble will be selected is 9/14.
Find Q1
114,950; 158,000; 230,500; 387,000; 389,950; 479,000; 488,800; 529,000; 575,000; 639,000; 659,000; 1,095,000; 5,500,000
Q1 = (230,500 + 387,000)/2 = 308,750
What is the definition of nonresponse?
Nonresponse occurs when an individual chosen for the sample can’t be contacted or refuses to participate.
Explain the 68 – 95 – 99.7 (EMPIRICAL) Rule. Be specific for each percentage.
- Approximately 68% of the observations fall within one 𝜎 of the mean 𝜇
- Approximately 95% of the observations fall within 2𝜎 of the mean 𝜇.
- Approximately 99.7% of the observations fall within 3𝜎 of the mean 𝜇.
The probability that it will rain today is 1/𝟓. If it rains on any given day, the probability that it rains the next day is 1/𝟑. If it does not rain on a particular day, the probability that it rains on the next day is 1/𝟔.
1. Draw a tree diagram
2. Determine the probability that it will rain on the second day.
2. 1/5
Find the smallest and largest values, the median, and the first and third quartile for the day class.
Test scores for a college statistics class held during the day are:
99; 56; 78; 55.5; 32; 90; 80; 81; 56; 59; 45; 77; 84.5; 84; 70; 72; 68; 32; 79; 90
Min = 32
Q1 = 56
M = 74.5
Q3 = 82.5
Max = 99
Find the standard deviation:
In a fifth grade class, the teacher was interested in the average age and the sample standard deviation of the ages of her students. The following data are the ages for a SAMPLE of n = 20 fifth grade students. The ages are rounded to the nearest half year: 9; 9.5; 9.5; 10; 10; 10; 10; 10.5; 10.5; 10.5; 10.5; 11; 11; 11; 11; 11; 11; 11.5; 11.5; 11.5;
s = 0.72
Carlos plays college soccer. He makes a goal 65% of the time he shoots. Carlos is going to attempt two goals in a row in the next game. A = the event Carlos is successful on his first attempt. P(A) = 0.65. B = the event Carlos is successful on his second attempt. P(B) = 0.65. Carlos tends to shoot in streaks. The probability that he makes the second goal GIVEN that he made the first goal is 0.90.
a. What is the probability that he makes both goals?
a. The problem is asking you to find P(A AND B) = P(B AND A). Since P(B|A) = 0.90: P(B AND A) = P(B|A) P(A) = (0.90)(0.65) = 0.585
Carlos makes the first and second goals with probability 0.585.