2
$\begingroup$

If I can take two trips to the office within five minutes, how many minutes will 130 trips take?

My attempt:

$$\frac{130\text{ trips}}{2} = 65\text{ trips}$$

$$65 \cdot 5 = 325 \text{ minutes}$$

$\endgroup$
  • $\begingroup$ What you have done looks good to me. $\endgroup$ – Gerry Myerson Mar 1 '13 at 1:26
  • $\begingroup$ What about "within" five minutes of each other? I forgot to mention that. $\endgroup$ – Quaxton Hale Mar 1 '13 at 1:29
  • $\begingroup$ I'm not sure how to interpret "within". Does it mean, it might take you less than $5$ minutes to make two trips? or does it mean you have to wait $5$ minutes between trips? Suppose you go to the office at noon, and come back at 12:01. When do you make the next trip to the office? $\endgroup$ – Gerry Myerson Mar 1 '13 at 3:08
  • $\begingroup$ I was thinking of it as you can start a trip only when the first one is finished, but in a period of 5 minutes. So, the max. time the first trip would take is 2.5 minutes before the next one starts. $\endgroup$ – Quaxton Hale Mar 1 '13 at 3:11
  • 1
    $\begingroup$ OK, so then you can do a complete trip every 2.5 minutes, so 130 trips in $(130)(2.5)$ minutes, which is the same answer you got: $(130)(2.5)=(65)(2)(2.5)=(65)(5)$. Unless I still don't understand the problem.... $\endgroup$ – Gerry Myerson Mar 1 '13 at 4:08
1
$\begingroup$

Hint: You can say you make $2/5$ of a trip to the office every minute. Now determine how many times this goes into $130$. To arrive at this idea, think about the units and cancellation when you divide/multiply.

$\endgroup$
0
$\begingroup$

Assuming time per trip is for a round trip. At $2.5$ minutes per trip, time to take $130$ trips is $130 * 2.5$ Counting the interstitial $5$ minute intervals, add $(130-1)*5$

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.