Q$5.$ Exercises $3\mathrm{.}3\mathrm{.}5,$ Problem $1.(1$pt$)$

Compare dep$\_$time, sched$\_$dep$\_$time, and dep$\_$delay. How would you expect those three numbers to be related

Q$6.$ Exercises $3\mathrm{.}3\mathrm{.}5,$ Problem $3.(1$pt$)$

What happens if you specify the name of the same variable multiple times in a select$()$Links to an external site. call?

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Q$7.$ Exercises $3\mathrm{.}3\mathrm{.}5,$ Problem $4.(1$pt$)$

What does the any$\_$of$()$Links to an external site. function do$?$ Why might it be helpful in conjunction with this vector?

variables $<-$ c$("$year$",$ "month", "day", "dep$\_$delay", "arr$\_$delay"$)$

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Q$8.$ Exercises $3\mathrm{.}3\mathrm{.}5,$ Problem $7.(1$pt$)$

Rename air$\_$time to air$\_$time$\_$min to indicate units of measurement and move it to the beginning of the data frame.

Why doesn$$t the following work, and what does the error mean?

flights $|>$ selectLinks to an external site.$($tailnum$)|>$ arrangeLinks to an external site.$($arr$\_$delay$)$

#$>$ Error in $`$arrange$()`$:

#$>$ In argument: $`.\mathrm{.}1=$ arr$\_$delay$`.$

#$>$ Caused by error:

#$>!$ object 'arr$\_$delay' not found

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Q$9.$ Exercises $3\mathrm{.}5\mathrm{.}7,$ Problem $1.(1$pt$)$

Which carrier has the worst average delays?

Extra Credit$(1$pt$)$:

Can you disentangle the effects of bad airports vs$.$ bad carriers? Why$/$why not?

Hint: think about

flights $|>$ group$\_$by$($carrier$,$ dest$)|>$ summarize$($n$())$

Q$10.$ Exercises $3\mathrm{.}5\mathrm{.}7,$ Problem $2.(1$pt$)$

Find the flights that are most delayed upon departure from each destination.