+321 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?
+128599 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
+128599 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
+128599 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
