I made these questions based on the Analyzing Patient Data lesson from the R programming lessons.

# Question 1

Suppose you had a dataframe named `df`

:

A | B | C | D | E |
---|---|---|---|---|

02 | 66 | 04 | 94 | 12 |

78 | 97 | 05 | 44 | 71 |

92 | 32 | 55 | 17 | 73 |

18 | 82 | 96 | 01 | 38 |

49 | 25 | 15 | 80 | 02 |

How could I ask R to return the 3rd and 5th rows of the dataframe?

`df[3,5]`

`df[c(3,5)]`

`df(c(3,5),)`

`df[c(3,5),]`

# Question 2

With the same dataframe as above, what would the following code produce?

```
max(df[2:4, c(1,4)])
```

- 92
- 96
- 78
- 97

**Misconceptions**

- Correct answer
- They have switched rows and columns
- Not understood that
`2:4`

means rows 2, 3, and 4 (not just 2 and 4) - Not understood that
`c(1,4`

is different from`1:4`