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A train leaves on station 80 miles/hour for 3.5 hours and 70 miles/hour for 2 hours to reach it's destination. What was the average seed for the entire trip.

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    $\begingroup$ Welcome to math.SE: In order to get the best possible answers, it is helpful if you say in what context you encountered the problem, and what your thoughts on it are; this will prevent people from telling you things you already know, and help them give their answers at the right level. $\endgroup$ Jul 24, 2017 at 23:16
  • $\begingroup$ im sorry sir.. yes i'll do it next time but this problem i really don't know the formula thanks.. $\endgroup$ Jul 24, 2017 at 23:22
  • $\begingroup$ No need to apologize! It's just always encouraged to see your work so finding the answer can be a learning experience. $\endgroup$ Jul 24, 2017 at 23:24

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$$ \begin{aligned} \text{Average speed}&=\frac{\text{total distance traveled}}{\text{total time traveled}}\\[5pt] &=\frac{80\cdot 3.5+70\cdot 2}{3.5+2}\\[5pt] &=\frac{420}{5.5}\\[5pt] &=76.\overline{36} \end{aligned} $$

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  • $\begingroup$ thanks a lot sir $\endgroup$ Jul 24, 2017 at 23:23
  • $\begingroup$ not sir. and your welcome :-) $\endgroup$
    – ervx
    Jul 24, 2017 at 23:31
  • $\begingroup$ @ervx "Ser", then? :) :) $\endgroup$
    – Deepak
    Jul 25, 2017 at 0:32
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Find the total distance travelled (by summing up the distances of each "leg" at a different speed), then divide by the total time for the trip.

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  • $\begingroup$ thanks sir its a big help to me $\endgroup$ Jul 24, 2017 at 23:23

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