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Stats Chapter 1-3
Intersession MTSAC
| Question | Answer |
|---|---|
| Statistics is the science of | hiding the truth or telling a lie |
| Fill in the blanks: The applications of statistics are commonly divided into two areas,_____ statistics and ______statistics | inferential and descriptive |
| Give three examples of qualitative variables | 1) Color 2) Gender 3) Grades |
| Give three examples of quantitative variables | 1) Room temperature 2) Number of students in a room 3) Amount of coffee in a cup |
| Qualitative or Quantitative? Luna randomly selected a red ace card from a shuffled deck of playing cards | Qualitative |
| Statistic or Parameter? A sample of 80 doctors had average salary of $12,000 per month | Statistic |
| Satistic or Parameter? The GPA of all students at the college is 2.95 | Parameter |
| Ordinal | qualitative measurement where order matters i.e s, m, l coffee |
| Nominal | qualitative measurement where order doesn’t matter ie names, colors, grades |
| Interval | 90%-100% |
| Ratio | 20 oz vs 12 oz |
| Discrete or continuous? The temperature of a cup of coffee is 68.7% | Continuous- it is not a countable amount |
| Discrete or continuous? The number of students in a Statistics class | Discrete- it is a countable amount, a whole number |
| Qualitative or Quantitative? The weight of people at a basketball game | quantitative |
| Qualitative or quantitative? The color of jersey of the players | qualitative |
| Sampling type? 25 students were selected from each of the F,S,J,S classes with 350,430,520 and 125 students respectively | stratified select a certain amount from each category |
| Sampling type? A stats student obtains data by interviewing his family members | convenience |
| Sampling type? The supervisor selected every 25th item for quality inspection | systematic |
| Sampling type? A medical researcher contacted every cancer patient from randomly selected 25 hospitals | cluster: randomly selected groups and then everyone is sampled from each group vs stratified: each group is chosen and then only a sampling from each group is used |
| A local newspaper reached out to 1200 voters by phone that were randomly generated by a computer | random |
| Standard deviation: find symbol and formula | S= √S^2 |
| Descriptive statistics: | Collect, organize, process and draw data and make conclusion |
| Inferential statistics: | Use result from data to make a prediction |
| Three characteristics of descriptive statistics | collection, process, organization, conclusion |
| Three characteristics of inferential statistics | Prediction, use of descriptive statistic data, data has already been collected |
| Given n=10, Ex=215 and Ex^2=4750 Find average. Round answer to one decimal place | 215/10 |
| Variance: find symbol and formula | ........S^2= n∑x^2-(∑x)^2)........ ........-----------------......... ...........(n(n-1))............... |
| Range rule of thumb | range/4 |
| Define "usual range" with equation and percentage value | 95% of data fall within: mean + 2S and mean - 2S |
| Find Pk | L=k/100 * (n) if decimal : round up and find the number in that location of the sorted data if whole number: find that number and the one before it. Take there sum and divide by 2 |
| Find xbar of the frequency distribution table by using class midpoints and class frequencies | Use calculator: L1,L2 |
| What is the empirical rule? | 68% of data will fall between xbar+S and xbar-S 95% of data will fall between xbar+2S and xbar-2S (usual) 99.7% of data will fall between xbar+3S and xbar-3S |
| Histogram | midpoints or boundaries and frequency |
| Ogive | boundaries and cum frequency |
| bar chart | limits and variables (like grades) |
| pie chart | percentage relative frequency and circle |
| stem plot | make sure you have a key, for 12 1|2 means 12 |
| frequency polygon | midpoints plus 2 extra and frequency |
| P(A)≤0.05 A is a __________ event | rare |
| Given a table with sum|p(sum) – enter data into | L1,L2 |
| P(6≤sum≤8) add up which numbers? | P(sum 6) +P(sum7)+P(sum8) |
| Addition rule P(A or B) | P(A) +P(B) - P(Aand B) |
| When filling in a venn diagram, always | Start with overlap |
| nCr what does each letter represent? | n #available, r- number we want, Combo no particular order |
| P(A and B) if independent events | P(A and B)= P(A)*P(B) |
| P(wake up with alarm)=0.9 what is chance you wouldn’t? | 1-0.9= .1 |
| P(A and B) if dependent events | P(A and B) = P(A)*P(B|A) |
| Conditional Probability | P(B|A) = P(A and B)/P(A) |
| Different symbols and names for mean | X ; µ; |
| 2 symbols for standard deviation | S and Ơ |
| Select 3 cards (no replacement, no particular order) P(3 aces) | = (4C3*48C0)/52C3 |
| Select 3 cards (no replacement, no particular order P(no aces) | (48C34C0)/52C3 |
| Select 3 cards (no replacement, no order) P(at least 1 ace) | = 1-P(no aces) |
| How Build Table To find expected value set up table net gain|P(net gain) then… | negative for spent, then pos+neg from winnings|P(you don’t win) then Prob you do. P(you dont win) is just the amount of people involved excluding you, ie 39/40. Prob you do is 1/40 |
| How do you find expected value # | set up table and plug values into your calculator using 1- var stats. If µ is 0 then its a wash, if it is negative then you lost money, if it is positive you earned money. An insurance would want it to be negative |
| Build sample space for three children | {BBB, BBG,BGG,GGG,GBG,BGB,GBB,GGB} |
| If you have a sample tree how do you find the probability of one scenario? | multiply the branch leading up to the tip of it |
| If you have a sample tree how do you find the probability of 3 scenarios? | multiply each branch then add, or if it is "at least" find the branches that dont work and subtract their sum from 1 |