Answer: Sue spends travelling 3.5 hours and spends stationary 2.5 hours
Explanation:
The attached image shows Sue's distance-time graph, from there we can observe the segments where she is stationary (lines with no slope) and the segments where she is travelling (lines with slope).
Time spent travelling:
From 2 p.m. to 3 p.m. is 1 hour
From 3:30 p.m. to 4 p.m. is 0.5 hour
From 5 p.m. to 6:30 p.m. is 1.5 hours
From 7:30 p.m. to 8 p.m. is 0.5 hour
Total time travelling=1 h+0.5 h+1.5h+0.5h=3.5 h
Time spent stationary:
From 3 p.m. to 3:30 p.m. is 0.5 hour
From 4 p.m. to 5 p.m. is 1 hour
From 6:30 p.m. to 7:30 p.m. is 1 hour
Total time travelling=0.5 h+1 h+1h=2.5 h