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Relative frequencies are calculated by dividing each value by the grand total.
Relative Frequency Table:
| Visit a Foreign Country | Attend Camp | Visit a National Park | |
|---|---|---|---|
| Grades 7-9 | 12.5 % | 20 % | 7.5 % |
| Grades 10-12 | 35 % | 10 % | 15 % |
Bar Chart:
Questions and Answers: See solution.
Trends in the Data: See solution.
Let's look at the given table about what students would most like to do during their summer vacation.
| Visit a Foreign Country | Attend Camp | Visit a National Park | |
|---|---|---|---|
| Grades 7-9 | 25 | 40 | 15 |
| Grades 10-12 | 70 | 20 | 30 |
We are asked to do four things.
Let's conquer these tasks one step at a time.
We will construct our relative frequency table using percents. To do so, we need to divide each frequency by the grand total and then multiply them by 100. First, to find the grand total, we have to add all the numbers in the table. Grand total: 25+40+15+70+20+30= 200 Now we can divide each cell by 200.
| Visit a Foreign Country | Attend Camp | Visit a National Park | |
|---|---|---|---|
| Grades 7-9 | 25/200* 100 | 40/200* 100 | 15/200* 100 |
| Grades 10-12 | 70/200* 100 | 20/200* 100 | 30/200* 100 |
After simplifying these values, we have the completed relative frequency table.
| Visit a Foreign Country | Attend Camp | Visit a National Park | |
|---|---|---|---|
| Grades 7-9 | 12.5 % | 20 % | 7.5 % |
| Grades 10-12 | 35 % | 10 % | 15 % |
We have decided to construct a bar chart showing the frequencies. Both a circle graph and a histogram would not have worked as well because it is not as easy to show side-by-side comparisons of the two types of students. We will use the y-axis to represent each frequency and the x-axis to represent the activity.
Next, we need to write and answer at least five questions involving conditional relative probability that can be answered by referring to the table. Please note that these are only a few examples of questions that could have been asked. There are many more options.
| Question | Answer |
|---|---|
| 1. Given that a student is in grade 7,8, or 9, what is the probability he/she wants to visit a foreign country? | 25 of the 80 students in grades 7-9 want to visit a foreign country. Therefore, the probability that a student wants to visit a foreign country, given that he/she is in year 7,8, or 9, is 2580= 516. |
| 2. Given that a student wants to visit a foreign country, what is the probability he/she is in grades 10-12? | 70 of the 95 students who want to visit a foreign country are in grades 10-12. Therefore, the probability that a student is in grades 10-12, given that he/she wants to visit a foreign country is 7095= 1419. |
| 3. Given that a student wants to attend a camp, what is the probability he/she is in grades 7-9? | 40 of the 60 students who want to attend a camp are in grades 7-9. Therefore, the probability that a student is in grades 7-9, given that he/she wants to attend a camp is 4060= 23. |
| 4. Given that a student wants to visit a national park, what is the probability he/she is in grades 10-12? | 30 of the 45 students who want to visit a national park are in grades 10-12. Therefore, the probability that a student is in grades 10-12, given that he/she wants to visit a national park is 3045= 23. |
| 5. Given that a student is in grades 10-12, what is the probability he/she wants to visit a national park? | 30 of the 120 students in grades 10-12 want to visit a national park. Therefore, the probability that a student wants to visit a national park, given that he/she is in grades 10-12, is 30120= 14. |
A big part of data analysis is describing trends in the data. For this data, let's use the relative frequency table constructed and the graph drawn.