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Ali and Bakar walked from A to B along the same route. Ali started his journey half an hour earlier than bakar .Bakar walked 6 km at an average speed of 4km/h for the whole journey. Both of them arrived at B at the same time. What was Ali's average speed
 May 24, 2017
 #1
avatar+202 
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examp. 12:00 start Ali                              Bakar:  4km ->1h

             12:30 start Bakar                         6km->xh    <=> x=3/2h <=> x=90 min +12:30= 2:00 

                                                                      

                                                                 arrived at the same time so Ali arrived at 2 so he do:

                                                                  6km->2h

                                                                  ykm->1h <=>y=3km so 3km/h is the Ali's average speed!!!

 I hope you understand!!!

 May 24, 2017
edited by Whitespy001  May 24, 2017
 #2
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+2

Average speed = Distance / Time

 

4= 6/ T, so T =6/4 =1.5 hours - that took Bakar to cover the 6 Km.

Ali's average speed = 6/ (1.5 + .5) =6 / 2 =3 Km/h - Ali's average speed.

 May 24, 2017
 #3
avatar+128089 
+2

 

 

 

Bakar's Distance divided by his rate  = his total time   =  6km / [ 4km/h ]  =  3/2 hr

 

And Ali's Distance  divided by his unknown rate , R,  rate  = his total time  = 6km / [ R km / h ]

 

And Bakar's time  plus 1/2 hr   =   Ali's time .......so

 

(3 / 2)   + (1/ 2)  = 6 / R   simplify

 

[ 6 + 2] / 4=   6 / R

 

[ 8 / 4]   = 6 / R

 

2 = 6 / R     and we can write

 

1/2 =  R / 6    multiply both sides by 6

 

3  = R      and Ali's rate  = 3 km / hr

 

 

cool cool cool

 May 24, 2017

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