Task
Fishing Adventures rents small fishing boats to tourists for day long fishing trips. Each boat can hold at most eight people. Additionally, each boat can only carry 1200 pounds of people and gear for safety reasons. Assume on average an adult weighs 150 pounds and a child weighs 75 pounds. Also assume each group will require 200 pounds of gear plus 10 pounds of gear per person.
- Write an inequality that illustrates the weight limit for a group of adults and children on the fishing boat and a second inequality that represents the total number of passengers in the fishing boat. Graph the solution set to the inequalities.
- Several groups of people wish to rent a boat. Group 1 has 4 adults and 2 children. Group 2 has 3 adults and 5 children. Group 3 has 8 adults. Which of the groups, if any, can safely rent a boat? What other combinations of adults and children are possible?
IM Commentary
This task is the last in a series of three tasks that use inequalities in the same context at increasing complexity in 6th grade, 7th grade and in HS algebra. Students write and solve inequalities, and represent the solutions graphically. The progression of the content standards is 6.EE.8 to 7.EE.4 to A-REI.12.
This particular task could be used for instruction or assessment. This task also has some elements of modeling with mathematics. To find reasonable estimates for the number of people that can rent a boat given certain restrictions, it is necessary to make some simplifying assumptions. In the case of this task we made assumptions about the average weight of adults and children, but this is only one possibility for solving a similar and more open ended problem.
Instead of renting a boat, the problem could also be set in the context of riding an elevator. Being cramped into an elevator often makes you wonder about weight restrictions.