Answer
The difference between the average numbers of awakenings during the night for 18-year-old men and 18-year-old women, as observed from the graph, is $1.1$.
Work Step by Step
We can observe from the given line graph, that for men at the age of 18 years, the average number of awakenings during the night is $2.9$.
Similarly, it can be seen from the graph that for women, at the age of 18 years, the average number of awakenings during the night is $1.8$.
Thus, the difference between the average numbers of awakenings during the night for 18-year-old men and 18-year-old women will be:
$2.9-1.8=1.1$.
