+0  
 
0
170
2
avatar+134 

Thank you CPhill you're thebest!!!!!!!!!!!!!!!!!!!!! <3

Supergirl  Nov 11, 2017
edited by Supergirl  Nov 11, 2017
edited by Supergirl  Nov 11, 2017
 #1
avatar+86859 
+1

a) Represent as a rational expression the time going to Germany.

The plane is being slowed by the wind so its rate is x - 50

The time going to Germany is  ....... Distance / Rate  =   9900 / [ x - 50]


b) Represent as a rational expression the time returning.

 

The plane is helped by the wind on the return trip....so its rate is  x + 50

And the time returning plus 4 hrs  = time going to Germany....so....we can represent (b) as

9900 / [ x + 50] + 4  =    [9900 + 4 [ x + 50] ]  / [ x + 50 ]


c) Write an equation representing the relationships between the times.

 

We have that

 

 9900 / [ x - 50] =    [9900 + 4 [ x + 50] ]  / [ x + 50 ]

 

d) What was the average rate of the plane in still air.

 

9900 / [ x - 50]  =  [  9900  + 4x + 200 ] / [ x + 50 ]       cross-multiply

 

9900 [ x + 50 ]  =  [ 10100 + 4x] [ x - 50]

 

9900x + 495000 =  10100x + 4x^2 - 505000 - 200x

 

9900x + 495000 =  9900x + 4x^2 - 505000      rearrange as

 

4x^2  - 1000000  =  0      divide through by 4

 

x^2   - 250000  = 0

 

x^2  =  250000            take the positive root of both sides

 

x =  500 km/ hr  =   speed in still air


e) How long did the round trip take?

 

Total time is   twice the return time plus 4 hours =   2 [  9900 / [ x + 50]   ]  + 4  = 

 

2 [ 9900 / 550 ] +  4  =

 

36   + 4  =     40  hrs

 

 

cool cool cool

CPhill  Nov 11, 2017
 #2
avatar
0

CPhill: 9,900 km is "round trip." One-way trip should be=9,900/2=4,950 km.

Guest Nov 11, 2017

31 Online Users

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.