Answer
a) Day 20
b) Day 65
c) Day 45
Work Step by Step
a) The second scatterplot (blue) shows the number of flies that died each day. The maximum value (peak in the scatterplot) occurs at around Day 20.
b) The "proportion of flies" that die refers to the mortality rate. The third scatterplot (red) depicts this; for the first 100 days, the maximum (peak) of this graph occurs at around Day 65.
c) The first scatterplot (green) shows the number of flies that are left living as time passes. It begins to level out into a horizontal line at around Day 45, meaning that the number of flies alive stopped changing drastically around that time.
