# Kmph to mph question. I didn't know where this should go

• Oct 23rd 2012, 09:34 AM
Ashir
Kmph to mph question. I didn't know where this should go
Can a mod please move this to the appropriate subforum?

Jodie travels at a speed of 80 km per hour for 2 hours 45 minutes. Work out how many miles she drives.

I understand 5 miles = 8 km but I don't know how to solve the question.
Sorry for my noobishness, thanks for the help!
• Oct 23rd 2012, 10:18 AM
skeeter
Re: Kmph to mph question. I didn't know where this should go
(80 km/hr)(2.75 hr) (5 mi/8 km)
• Oct 23rd 2012, 10:19 AM
Ashir
Re: Kmph to mph question. I didn't know where this should go
?
• Oct 23rd 2012, 10:22 AM
topsquark
Re: Kmph to mph question. I didn't know where this should go
Quote:

Originally Posted by Ashir
Can a mod please move this to the appropriate subforum?

Just a quick comment: Algebra is fine for this topic.

-Dan
• Oct 23rd 2012, 10:33 AM
Ashir
Re: Kmph to mph question. I didn't know where this should go
Okay, thanks.
• Oct 23rd 2012, 10:53 AM
topsquark
Re: Kmph to mph question. I didn't know where this should go
Quote:

Originally Posted by skeeter
(80 km/hr)(2.75 hr) (5 mi/8 km)

Let's try it by writing it this way.

$\text{80 km/hr} = \frac{80~km}{1~hr}$

$\left ( \frac{80~km}{1~hr} \cdot \frac{2.75~hr}{1} \right ) \cdot \frac{5~mi}{8~km}$

The units cancel out in the same way as numbers do. So in the ( ) is the distance the car travels in km. (The units hr cancel out by division.) This comes from the equation d = vt. Then the last factor converts km into miles. In this case the km cancels out.

-Dan
• Oct 23rd 2012, 11:00 AM
Ashir
Re: Kmph to mph question. I didn't know where this should go
...I'll just ask my teacher, thanks though