The Chicken & Rabbit problem is a great math and logic question. Here is the question:
There are some chickens and rabbits. The number of total legs is {number} and the total number of eyes is {number}. How many chickens/rabbits are there?
There are also many different ways to express this:
There are some {first thing} and {second thing} The number of total {first part of thing} is {first number} and the total number of {second part of thing} is {second number}. How many chickens/rabbits are there?
For instance, you can sub first thing for motorcycles and second thing for cars. You can also sub it for caterpillars and centipedes, and 3-legged benches and 4-legged tables! Then the same thing for first part of thing, second part of thing (wheels, seats, legs…), and so on. Here’s an example question story:
A school is taking a pool field trip, planned by Principal Skerb. To make things fair, every class will have a chance to go. 140 children are selected to go. Mr. Skerb has stocked up on volunteer parents who will drive ordinary cars. A van can transport 5 children, and cars can transport 3 children each. Plus, 40 vehicles may only be rented.
“What can I DO?!?! I can’t find out how many vehicles to pay for!” Principal Skerb yelled in frustration one day, pulling his twirly mustache and stuffing them bunch by bunch into his mug of coffee. The coffee slowly dripped down the polished oak table, onto the carpet. Mr. Skerb looked down at his precious cream-yellow carpet. He sighed. He decided to replace the carpet later. He ended the call and covered the spill up messily with some napkins. “Aha!” Mr. Skerb cried. “If I can substitute this carpet with wood boards, then surely I can sub buses for cars!” Mr. Skerb then scribbled down:
140 students will go. 1 van holds 5, and one car holds 3. 40 vehicles can only be used.
If we use only vans, then 40 vehicles × 5 seats per van = 200 seats to use. But only 140 kids will go, so we will have 60 too many empty spaces. If we sub 1 van for a car, then the seat difference is 2. Since we need to subtract 60 seats, let's divide 60 ÷ 2 which is 30.
So we will use 30 cars! 40 vehicles will be used, so 40 - 30 is ten, so we will use 10 vans!Mr. Skerb calculated his budget and took a bite out of the warm brownie he just snatched from the school kitchen pantry. It had the perfect fudgy taste, and Mr. Skerb now was able to calculate budgets!
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Later, Mr. Skerb visited a farm with his toddler niece Rosa. They saw a coop with chickens and rabbits. “Look!” Rosa said. “A chicken has 2 legs but a rabbit has four!”
“Yes, Rosa,” Mr. Skerb said.
“They both have two eyes!”
“Wow, good job! You are so smart!”
“Zookeeper, how many legs do all the chickens have altogether?”
Farmer Julian looked up and smiled slyly. He replied, “The chickens and the rabbits total have 50 legs. But they total have 26 eyes. There are 13 total creatures. Can you figure it out and be a detective?”
“Uncle, help me!”
Mr. Skerb dug out his memory of the budget planning. He grinned and calculated the answer.
What do you think the answer is?
