For an introduction to probability, I am experimenting with using dplyr (well, tidyverse) to connect programming concepts to the idea of conditional probability. In my code below, I am using `mutate`

to store numbers that I need later (simply the "numerator" and the "denominator"). My query is this: does anyone have a cleaner way of doing this calculation?

Example: Compute the probability that a randomly selected passenger on the Titanic was female *given* that the passenger was at least 35 years old.

```
library("tidyverse") #for data wrangling tools
library("titanic")
tdf <- titanic_train #training set of Titanic data
conditional_probability <- tdf %>%
filter(Age >= 35) %>%
mutate(denominator = n()) %>%
filter(Sex == "female") %>%
mutate(numerator = n()) %>%
summarize(unique(numerator/denominator))
```