如何在R中使用润滑时间制作ggplot2散点图？

I have a set of hours (some greater than 24) that represents the time some students spent on studying sessions. I want to make a scatter plot of studying time and exam results using ggplot2. The thing is the total time data is in lubridate's time format, how do I plot using this? Example:I have a set of hours (some greater than 24) th