Question 1161456

I'm studying for the SAT's and this question popped up.

Corrine drives d miles to her office at an average speed of 50 miles per hour.  Returning home, she travels by the same route and averages 60 miles per hour.  If her trip home is 10 minutes shorter than her trip to her office, what is the value of d?

The practice book shows the equations would then be {{{ d=50(t+1/6) }}} and {{{ d=60(t)}}}.  It then shows it would substitute {{{ d=50(t+1/6)}}} into {{{ 50(t+1/6)=60t}}}.

I just don't understand where they got the 1/6 from in the word problem.  Could you please explain where the 1/6 came from so I can better understand how the equation was set up?
<pre>The 10 minutes, when converted to hours gives you: {{{matrix(1,6, 10/60, "=", 1/6, of, an, hour)}}}
If that's how the book showed the setup-equations, I totally disagree. To me, it's unnecessary to find "t" or time, and then use that to find d, the distance.
Unless, of course, you're asked to find the time, but if it's just "d" or the distance you need, I'd do it differently, and go STRAIGHT for the answer.
I'm an avid proponent of getting straight to the answer, and so, my preference would be the following TIME equation: {{{highlight_green(matrix(1,7, d/50, "=", d/60 + 10/60, or, d/5, "=", d/6 + 10/6))}}}
I'd then solve that for d.
The time on each section of the SAT is short - it's not like the Regents where you have like a "ton" of time - and the less time you spend on each problem, the better off you are!