Question

Taylor drives 5 miles in 10 minutes. She stops at a light for 2 minutes. She then travels another 10 miles in 8 minutes. What was her average speed?

Answers -

A. 45 mph
B. 2 mph
C. 0.9 mph
D. 1.8 mph

Answer 1

Answer:

A. 45 mph

Step-by-step explanation:

Notice that your units do not match the answers. Time in your problem is in minutes, but you need the answer in miles per HOUR. So first we convert,

1 hour = 60 minutes

$10 mins \times \dfrac{1hr}{60mins}=0.167hrs\\\\2 mins \times \dfrac{1hr}{60mins}=0.033hrs\\\\8 mins \times \dfrac{1hr}{60mins}=0.133hrs$

So now we have our new given:

d₁ = 5 miles           d₂=0 miles (It was not moving)        d₃ = 10 miles

t₁ = 0.167 hrs           t₂ = 0.033 hrs                                   t₃ = 0.133 hrs

To get the average speed, you get the sum of distances and divided it by the sum of time:

$\bar{v}=\dfrac{d_1+d_2+d_3}{t_1+t_2+t_3}\\\\\bar{v}=\dfrac{5miles+0miles+10miles}{0.167hrs+0.033hrs+0.133hrs}\\\\\bar{v}=\dfrac{15miles}{0.333hrs} = 45.05 mph$

So the answer is 45.05mph or 45 mph.