Solution:
the farmer needs 3 hens to produce 12 eggs in 6 days
This is a classic problem that many people get wrong because they reason that half of a hen cannot lay an egg, and a hen cannot lay half an egg. However, we can get a satisfactory solution by treating this as a purely mathematical problem where the numbers represent averages.
To solve the problem, we first need to find the rate at which the hens lay eggs. The problem can be represented by the following equation, where RATE is the number of eggs produced per hen·day:
1½ hens × 1½ days × RATE = 1½ eggs
We convert this to fractions thus:
3/2 hens × 3/2 days × RATE = 3/2 eggs
Multiplying both sides of the equation by 2/3, we get:
1 hen × 3/2 days × RATE = 1 egg
Multiplying both sides of the equation again by 2/3 and solving for RATE, we get:
RATE = 2/3 eggs per hen·day
Now that we know the rate at which hens lay eggs, we can calculate how many hens (H) can produce 12 eggs in six days using the following equation:
H hens × 6 days × 2/3 eggs per hen·day = 12 eggs
Solving for H, we get:
H = 12 eggs /(6 days × 2/3 eggs per hen·day) = 12/4 = 3 hens
Therefore, the farmer needs 3 hens to produce 12 eggs in 6 days.