soluja2003 wrote:It takes Carlos 9 minutes to drive from home to work at an average of 22 miles per hour. How many minutes will it take Carlos to cycle from home to work along the same route at an average of 6 miles per hour?
A. 26
B. 33
C. 36
D. 44
E. 48
Thanks!
The quickest way to do this question is by estimating using the ratio of speeds.
At 22 mph it took 9 minutes. 22mph is a bit less than 4 times 6mph, therefore it should take a bit less than 4*9=36. Only one choice is a bit less than 36: choose (b).
We could also solve this the more traditional way, using the distance/rate/time formula.
We know that d = r * t
When r=22, t=9 minutes = 9/60 hours (or 3/20 hour after reducing).
So, d = 22 (3/20) = 66/20 = 33/10
If we let r = 6, we can now solve for t:
33/10 = 6t
t = (33/10)/6
t = 33/10 * 1/6 = 33/60. Since one hour is 60 minutes, that give us a time of 33 minutes.
