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My friend sets out walking at a speed of 3 miles per hour. I set out behind her 5 minutes later at 5 miles per hour. For how many minutes will my friend have been walking when I catch up to her?

 Mar 27, 2022
 #1
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Let the time it takes you to catch up to your friend==T

 

5T ==3 [T  +  5],  solve for T

 

5T ==3T  + 15

 

5T - 3T ==15

 

2T == 15

 

T ==15 / 2 ==7.5 minutes -for you to catch up to her

 

7.5  +  5 ==12.50 minutes - your friend had been walking when you caught up to her.

 Mar 27, 2022
 #2
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5 min = 1/12 hr      in five minutes your friend will have a  3 m/hr * 1/12 hr = 1/4 mile head start

    You are walking two miles per hour faster and will take    1/4 m / 2 m/hr = 1/8 hr to catch her = 7.5 mins

         7.5 + 5 = 12.5 mins

 Mar 28, 2022
edited by ElectricPavlov  Mar 28, 2022

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