Ratios: Javier drives the 55 miles from Alphaville to Baileyburg in 55 minutes...

HaveAQUESTION

New member
Joined
May 3, 2012
Messages
9
[COLOR=rgba(56, 61, 66, 0.8)][FONT=&quot]Javier drives the 55 miles from Alphaville to Baileyburg in 55 minutes, and then drives back to Alphaville in 45 minutes. What is his average speed for the entire round trip?

(A) 45 mph
(B) 55 mph
(C)60 mph
(D)66 mph

So if avg speed is total distance divded by time then I would have multiply 55 x 2 (which is 110) and have to add 45 minutes plus 55 minutes (110 miles/100 minutes) and would get 1.1 but I dont see that on the answer choices. Where am i going wrong here?
[/FONT][/COLOR]
 
Javier drives the 55 miles from Alphaville to Baileyburg in 55 minutes, and then drives back to Alphaville in 45 minutes. What is his average speed for the entire round trip?

(A) 45 mph
(B) 55 mph
(C) 60 mph
(D) 66 mph

... I would have multiply 55 x 2 (which is 110) and have to add 45 minutes plus 55 minutes (110 miles/100 minutes) and would get 1.1 but I dont see that on the answer choices. Where am i going wrong here?
You have forgotten to notice the units.

110 miles divided by 100 minutes gives 1.1 miles per minute.

The answer choices are given in terms of different units (miles per hour).

Do you know how to convert 1.1 miles per minute into the equivalent number of miles per hour? :cool:
 
You have forgotten to notice the units.

110 miles divided by 100 minutes gives 1.1 miles per minute.

The answer choices are given in terms of different units (miles per hour).

Do you know how to convert 1.1 miles per minute into the equivalent number of miles per hour? :cool:
I multplied 1.1 by 60 and got 66. Thank you.
 
You got it! :)

Other conversions require more thought. Like, converting 1.1 mi/min to ft/sec.

If you're interested and have the time, google keywords converting rates using dimensional analysis and check out how units in ratios can cancel just like factors cancel. It's a handy method, when working with paper and pencil.
 
Top