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1.Twelve hungry teenagers can devour a very large pizza in 20 minutes. How many teenagers would it take to finish a very large pizza in 15 minutes? (Assume that all teenagers eat pizza at the same rate.)

 

2.Tina lives 30 miles away from her work, and she normally drives at 45 miles per hour. If she wants to get to work 10 minutes earlier, how fast should she drive to work, in miles per hour?

 

3.All of the members of our spray-painting team paint at the same speed. If 5 team members can paint a certain wall in 27 minutes, then how many minutes would it take 15 of our team members to paint the same wall?

 Jan 5, 2021
 #1
avatar+117576 
+3

1.Twelve hungry teenagers can devour a very large pizza in 20 minutes. How many teenagers would it take to finish a very large pizza in 15 minutes? (Assume that all teenagers eat pizza at the same rate.)

 

This is known as a  "see-saw" problem

 

12 * 20  =   15 *  x

 

12 * 20   / 15   =  x

 

240 / 15 =   x

 

16   teenagers

 

 

cool cool cool

 Jan 5, 2021
 #2
avatar+117576 
+3

2.Tina lives 30 miles away from her work, and she normally drives at 45 miles per hour. If she wants to get to work 10 minutes earlier, how fast should she drive to work, in miles per hour?

 

Distance / Rate  = Time

 

30 m / ( 45 m/hr)  =    (30/45) h =  2/3 h    =  40  min it takes her  to get to work  driving at 45 mph

 

So.....she  needs to cover 30 miles  in 10 minutes less =  30 min

 

So....she needs to cover  1 mile per minute =  60 mph

 

cool cool cool

 Jan 5, 2021
 #3
avatar+117576 
+3

3.All of the members of our spray-painting team paint at the same speed. If 5 team members can paint a certain wall in 27 minutes, then how many minutes would it take 15 of our team members to paint the same wall?

 

Let's solve this with some logic

 

15  team members can do 3  times the  work of 5

 

So....the time it takes  them  must  just  be 1/3  of  27   =    9  minutes

 

 

cool cool cool

 Jan 5, 2021
edited by CPhill  Jan 5, 2021

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