Answer:
D. 3:00 p.m.
Step-by-step explanation:
d = Distance = 320 miles
s = Speed = [tex]60\ \text{mph}=\dfrac{60}{3600}=\dfrac{1}{60}\ \text{miles/s}[/tex]
Time taken is given by
[tex]t=\dfrac{d}{s}\\\Rightarrow t=\dfrac{320}{\dfrac{1}{60}}\\\Rightarrow t=19200\ \text{s}[/tex]
40 minutes break is [tex]40\times 60=2400\ \text{s}[/tex]
Total time taken is [tex]19200+2400=21600\ \text{s}=\dfrac{21600}{60\times 60}=6\ \text{hours}[/tex].
So, the entire trip took 6 hours. 6 hours after 9 a.m. is 3 p.m.