- Write a for loop that calculates the mean bill length for each species in the
`penguins`

data set (don’t use `group_by()`

) and saves them as `species_means`

.

- Turn #1 into a function called
`species_mean`

that lets the user determine which variable to calculate the mean over.

- Create a list
`penguins_island`

that separates the penguins data by island.

- Apply
`map()`

to find the number of observations for each year.

- Apply
`map()`

to calculate the mean body weight for each island.

- Rework #5 to return a numeric vector with values rounded to 1 decimal place.