Final answer:
It takes 3 people 40 minutes to fold laundry, so the constant of proportionality is 120 person-minutes. For 5 people to fold the same amount, it would take 24 minutes as time varies inversely with the number of people.
Step-by-step explanation:
The amount of time it takes to fold laundry varies inversely with the number of people folding it. If it takes 3 people 40 minutes to fold a pile of laundry, we can find the constant of proportionality (k) by multiplying the number of people by the time it takes, so k = 3 people × 40 minutes = 120 person-minutes. Now, to find out how long it will take for 5 people to fold the same pile, we use the formula time = k / number of people which in this case is time = 120 person-minutes / 5 people. Calculating this gives us time = 24 minutes.