The amount of time p people to paint d doors varies directly with the number of doors and inversely with the number of people. Four people can paint 10 doors in 2 hours How many people will take to paint 25 doors in 5 hours?
1 Answer
Apr 18, 2017
Explanation:
The first sentence tells us that the time
#t = (kd)/p" "# ... (i)
for some constant
Multiplying both sides of this formula by
#(tp)/d = k#
In the second sentence, we are told that one set of values satisfying this formula has
So:
#k = (tp)/d = (2*4)/10 = 8/10 = 4/5#
Taking our formula (i) and multiplying both sides by
#p = (kd)/t#
So substituting
#p = ((4/5)*25)/5 = 20/5 = 4#