What’s your preferred wake-up time? Whether you believe it or not, your preference is likely to change during your lifetime.

People in their twenties love a lie-in, while those in their fifties love to leap out of bed at the crack of dawn.

No, it’s not laziness; it’s all about brain chemistry. If your school is still expecting you to function earlier than 10 am, they’re behind the times.

The data below show responses of 100 twenty-year-olds and 100 fifty-year-olds when asked their preferred wake-up time.

By hand, construct standardised histograms for each sample, and plot them on the same axes, aligned vertically so you can see how the two distributions compare. Use histogram bins of half-hours. The first bin should cover the interval [6:00, 6:30), which you should render on the plot as [6, 6.5).
In later chapters, you’ll learn how to test whether it’s plausible that two samples like this come from the same underlying probability distribution. Based on your plots, what do you guess is the answer in this case?