In March, Kurt ran an average of 1.5 miles an hour. If by June he had

There are information provided
- K used to run speed @ 1.5 miles/ 1 hour
- Now he runs faster
- He runs 10 secs faster per 1 mile
- And question ask about time in "hours" it uses to run in "1 mile"

So we should focus on question which is "per hours" and "per 1 mile"

Let's try to calculate
1. We convert the first speed into "1 mile" unit
1.5 mile per 1 hour
1 mile per 1*1/1.5 hour = 2/3 hour = 40 mins

2. We convert mins into secs so that we can calculate it with the pace which is "secs per 1 mile"
40mins = 2,400 secs

3. We reduce the the secs by 10 secs as the question provided information "he had increased his pace by 10 seconds per mile"
So the time spent after the increasing speed is
2,400 - 10 = 2,390 secs per 1 mile
(**BE CAREFUL**; 10 secs FASTER means that he runs faster and the time spent should be reduced NOT increased.)

4. Now we convert our calculation into what question want. The question want "hours" spent per "1 mile"
what we have is 2,390 secs per 1 mile.
we convert secs per mile into hour per mile by divide it with 60^2
(**TRICK**; sometime we are not sure whether we should divide or multiply when we have to convert some units. The easy way that I do is just think like should it have to go larger or smaller? eg. convert 100,000 secs into hrs. Just think like should hrs be a lot larger than 100k secs or a lot smaller than 100k secs? larger NO! we go smaller, then we just divide it with 60*60. For me think like this can easily eliminate the confusion during rush time)

so the answer is = 2,390/60^2
I believe that answer is "A" (Please give me suggestion if I calculate something wrong )


My Learning
- I believe that there is another approach where we start to convert from 10secs/1mile into n secs / 1.5mile and add it with the 1hr/1.5mile. This approach can lead to answer too. But it requires a little more calculation. That's why I think we should focus on question. The question ask about time per 1 mile. So convert per 1mile to per 1.5mile may need another convert back to per 1mile in the end.. This little trick could reduce time using by 15-30secs.