<p>Robin walked 3 miles to a particular grocery to buy her favorite spaghetti sauce. If she doubled her pace on the way home, and the round trip took 80 minutes, what was her pace walking to the store?</p>
<pre><code>(A) 1.66 miles per hour
(B) 3.38 miles per hour
(C) 4.94 miles per hour
(D) 6.75 miles per hour
(E) 9.53 miles per hour
</code></pre>
<p>Whats the best way to do that???</p>
<p>(B)</p>
<p>Let's calculate for time:</p>
<p>Let v1 be the initial speed (what we want to find). We know that 80 min is equal to 4/3 hours.</p>
<p>So,</p>
<p>3/v1 + 3/(2v1) = 4/3. </p>
<p>The distance divided by the first speed gives the amount of time it takes her to go to the store. The distance divided by the second speed gives the amount of time it takes to return home. Together, they add up to 4/3 hour.</p>
<p>So, solving for v1, we arrive at the answer.</p>