Wednesday, May 1, 2013

pigs and chickens

A farmer looks out into the barn yard and sees the pigs and chickens. He says to his daughter, I count 40 heads and 100 feet . How many pig s and how many chicken are there?


Solution:



Let's use 
P-#pigs
C-#chickens 
I count 40 heads: every animal has a head so... 
P%2BC=40 

...and 100 feet... 
Pigs have 4 feet so 4P is the number of Pig's feet he sees and by the same thinking 2C is how many Chicken's feet. So... 
4P%2B2C=100 
To make our work easier we'll divide every term by 2... 
2P%2BC=50 

We have 2-equations and 2-unknowns: 
P%2BC=40
2P%2BC=50 
From the top equation we can say
C=40-P 
Next 
2P%2BC=50 
becomes... 
2P%2B%2840-P%29=50 
From which we can quickly deduce that there are 10 pigs. And since there are 40 animals there must be 30 chickens. 
:)

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