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

A. 45 mph

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 * (1hr)/(60mins)=0.167hrs\\\\2 mins * (1hr)/(60mins)=0.033hrs\\\\8 mins * (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}=(d_1+d_2+d_3)/(t_1+t_2+t_3)\\\\\bar{v}=(5miles+0miles+10miles)/(0.167hrs+0.033hrs+0.133hrs)\\\\\bar{v}=(15miles)/(0.333hrs) = 45.05 mph`

So the answer is 45.05mph or 45 mph.