Algebra II word problem

Algebra
Tutor: None Selected Time limit: 1 Day

UMES maintain a courier plane to transport company executives back and forth between headquarters and plant 250 miles away.  On the first leg the pilot flew 10 mph.  on the return leg the average was 30mph.  If the pilot spent a total of four hours in the air, what would the average speed of the courier plane be with no wind? 

Apr 22nd, 2015

"On the first leg the pilot flew 10 mph".    This statement describes a situation that is not possible. A plane cannot fly at a speed of only 10 mph.

Therefore the problem was written incorrectly.

Please correct it and I'll be happy to solve it.

Thanks.

Apr 22nd, 2015

Zelon Pharmaceuticals maintain a courier plane to transport company executives back and forth between the company headquarters and the main manufacturing plant 250 miles away.  Today the pilot flew from headquarters to the plant, picked up the chief of Operations, and returned to headquarters.  On the first leg of the trip, the pilot flew against a headwind averaging 10 mph.  On the return leg, the average tailwind was 30 mph.  If the pilot spent a total of four hours in the air, what would the average speed of the courier plane be with no wind?

Apr 22nd, 2015

I wrote it exactly the way the teacher wrote the word problem.  I don't understand it neither.

Apr 22nd, 2015

Ah, THAT'S more like it :)

I'll have this for you in a few minutes.


Apr 22nd, 2015

okay, thxs

Apr 22nd, 2015

Let x = speed of the plane without wind

time going = distance/speed = 250 / x-10

time returning = 250 / x+30

total time was 4 hours

So,  250/x-10 + 250/x+30 = 4

The common denominator is (x-10)(x+30)

We multiply both sides by the common denominator to get

250(x+30) + 250(x-10) = 4(x-10)(x+30)

250x + 7500 +250x -2500 = 4x^2 + 80x - 1200

500x + 5000 = 4x^2 + 80x -1200

4x^2 - 420x - 6200 = 0

2x^2 - 210x - 3100 = 0

Using quadratic formula

x = 118 mph


Apr 22nd, 2015

I have not heard from you.  Are you still working on the problem.

Apr 22nd, 2015

I have not heard from you.  Are you still working on the problem.

Apr 22nd, 2015

thank you.  You explained it very well.

Apr 22nd, 2015

You're welcome.

Apr 22nd, 2015

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