1. Mutate the data frame so that it includes a new variable that contains the average speed, avg_speed traveled by the plane for each flight (in mph). What is the tail number of the plane with the fastest avg_speed? Hint: Average speed can be calculated as distance divided by number of hours of travel, and note that air_time is given in minutes. If you just want to show the avg_speed and tailnum and none of the other variables, use the select function at the end of your pipe to select just these two variables with select(avg_speed, tailnum). You can Google this tail number to find out more about the aircraft. Answer Question 8 to the left.
data("nycflights")


nycflights <- mutate(nycflights , avg_speed = distance / air_time)

nycflights %>%
  group_by(tailnum) %>%
  summarise( avg_speed = mean(avg_speed) ) %>%
  arrange(desc(avg_speed))
## # A tibble: 3,490 × 2
##    tailnum avg_speed
##      <chr>     <dbl>
## 1   N526AS  8.487633
## 2   N637DL  8.433246
## 3   N66051  8.411864
## 4   N907JB  8.410526
## 5   N522VA  8.382353
## 6   N5BTAA  8.322917
## 7   N654UA  8.309701
## 8   N382HA  8.247184
## 9   N75861  8.246154
## 10  N5DRAA  8.218600
## # ... with 3,480 more rows