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Two riders are in a bike race. The second rider starts half an hour late but rides 4 miles per hour faster than the first rider. If they both finish 3 hours after the race starts, how fast are they each riding? 16 mph and 20 mph 20 mph and 24 mph 17.5 mph and 22.5 mph 24 mph and 28 mph

Respuesta :

Answer:Option (ii) is correct i.e. 20mph and 24mph


Step-by-step explanation:

Let us assume that the two riders are A and B

 A                                                B

Let speed of A be v mph         then speed of B will be (v+4)mph

Time taken by A =3h              Time taken by B=3-0.5= 2.5h

Since distance travelled by both is the same

Distance=[tex]Speed\times Time[/tex]

[tex]3\times v=2.5\times(v+4)[/tex]

[tex]3 \times v=2.5\times v+10[/tex]

[tex]3\times v-2.5\times v=10[/tex]

[tex]0.5\times v=10[/tex]

Dividing both sides by 0.5

v=[tex]\frac{10}{0.5}[/tex]

[tex]v=20[/tex]mph

i.e Speed of A=20mph

∴ Speed of B=20+4 =24mph

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