Question

It takes 5 carpenters 5 hours to make 5 chairs. How long would it take 100 carpenters to make 100 chairs?

Answer 1

# of chairs = x
# of carpenters = y
Time = t

# of chairs (y) is directly proportional to tx
y = t * x

Therefore, y1 * t1 / x1 = y2 * t2 / x2
y1, t1, x1 = 5 and y2, x2 = 100 = > t2 = 5

Answer: 5 minutes

Answer 2

I hour because, one of the 5 carpenters built one chair in one hour, so one of the 100 carpenters would build one chair in one hour, there are only 95 more carpenters, nothing else different.
Hope I helped!