Respuesta :
Answer:
The average speed for the journey is 6.4 mph.
Step-by-step explanation:
Given:
If you walk for 45 minutes at a rate of [tex]$4 \mathrm{mph}$[/tex] and then run for 30 minutes at a rate of [tex]$10 \mathrm{mph}$[/tex], then how many miles have you gone at the end of one hour and 15 minutes Find the average speed for the journey
Step 1 of 1
We can compute the walking distance and running distances separately, then add them.
You walk for 45 minutes, which is [tex]\frac{3}{4}$[/tex] hours, at a rate of [tex]$4 \mathrm{mph}$[/tex], so the walking distance is [tex](4 \mathrm{mph})\left(\frac{3}{4}\right.$ hours $)=3$[/tex] miles. You run for 30 minutes, which is [tex]\frac{1}{2}$ hour, at a rate of $10 \mathrm{mph}$[/tex], so the running distance is [tex]$(10 \mathrm{mph})\left(\frac{1}{2} h o u r\right)=5$[/tex] miles.
So the total distance you cover is 3+5=8 miles.
Now we can also compute the average speed for the journey.
You covered 8 miles in [tex]$\frac{5}{4}$[/tex] hours, so your average speed was
[tex]$\begin{aligned}&\frac{8 \text { miles }}{\frac{5}{4} \text { hours }}=\frac{8}{\frac{5}{4}} \mathrm{mph} \\&\frac{32}{5} \mathrm{mph}=6.4 \mathrm{mph}\end{aligned}$[/tex]
