Ann runs at a pace of 6 miles per hour. How many miles can she run in 30 minutes?

Ann runs at a pace of 6 miles per hour. How many miles can she run in 30 minutes?

Solution:

This is a proportion:

Find the rate of change between the two points: (8, 1) and (4, 2) where x is in months and y is in inches.

Rate of change is computed using slope: 
m=(y2-y1)/(x2-x1)
so 
m=(2-1)/(4-8)=-1/4 
that means the rate is falling at 0.25 inches every month

A snail can move 8 inches in 11 minutes. At this rate, how many feet can it move in 33 hours?

8 in = 8/12 ft
11 mun = 11/60 hr 
r=(8/12)/(11/60)=(8/12)(60/11)=40/11 ft/hr 
d=r*t=(40/11)*33=120 ft

John can paint a fence in 15 hours. his brother can paint it in 18 hours. If john paints for 8 hours alone and turns the rest over to his brother, how long will it take his brother to finish painting the fence?

after 8 hours john has done 8/15 of the job. We can set up a proportion to determine how long his brother will take:

that is 8 hours and 24 minutes