1. Consider the relation race. What is displayed by len( race ) •10 •3 •9 •4 2. Consider the relation race. Which code would display the number is runners from each country? •race["country"]. value_counts( ) •country.value_counts( ) •race["country"].info( ) •race.value_counts( ) 3. Which rows of data will be displayed by race.tail ( ) •last five rows of the table •first five rows of the table • first three rows of the table • last three rows of the table
1. The code `len(race)` will display the number of rows in the relation race.
2. The code `race["country"].value_counts()` will display the number of runners from each country.
3. The code `race.tail()` will display the last five rows of the table.
1. The expression "len(race)" gives the total number of elements in the relation race. So, "len(race) • 10 • 3 • 9 • 4" would simply display the result of multiplying the length of the race relation by 10, 3, 9, and 4 respectively.
2. To display the number of runners from each country in the relation race, the correct code would be "race['country'].value_counts()". This code will count the occurrences of each unique value in the 'country' column of the race relation and display the counts for each country.
3. The code "race.tail()" will display the last five rows of data in the race relation.
1. To get the answer, you need to understand the context of the question. It is asking about the relation "race" and wants to know the result of len(race) multiplied by 10, 3, 9, and 4.
To find the answer, follow these steps:
- First, check if you have the relation "race". If not, you'll need to obtain it somehow.
- Once you have the "race" relation, calculate the length of the relation using the len() function. This will give you the number of elements in the relation.
- Finally, multiply the length of race by each of the given numbers (10, 3, 9, and 4) to get the result.
For example, if the length of "race" is 20, the calculations will be:
- len(race) • 10 = 20 • 10 = 200
- len(race) • 3 = 20 • 3 = 60
- len(race) • 9 = 20 • 9 = 180
- len(race) • 4 = 20 • 4 = 80
2. To get the number of runners from each country in the relation "race", you need to select the appropriate code snippet that will provide this information. Let's analyze the available options:
- race["country"].value_counts(): This code will display the count of unique values in the "country" column of the "race" relation. It will give you the number of runners from each country.
- country.value_counts(): This code is incorrect because it is missing the relation name "race" before the dot notation. It won't produce the desired result.
- race["country"].info(): This code will display information about the "country" column in the "race" relation, such as the data type and the number of non-null values. It won't give you the number of runners from each country.
- race.value_counts(): This code will display the count of unique values in the entire "race" relation across all columns. It won't provide specifically the number of runners from each country.
Therefore, the correct code to display the number of runners from each country in the "race" relation is: race["country"].value_counts().
3. To determine which rows of data will be displayed by the code race.tail(), you need to understand what the ".tail()" function does.
The ".tail()" function is used to display the last rows of a relation. In this case, since there is no specified number, the default number of rows to display is 5.
So, by executing the code race.tail(), you will get the last five rows of data from the "race" relation.