Henry Ernest Dudeney/Puzzles and Curious Problems/147 - Blindness in Bats

Puzzles and Curious Problems by Henry Ernest Dudeney: $147$

Blindness in Bats

A naturalist was investigating (in a tediously long story) whether bats are in fact actually blind.

He discovered that blindness varied.

Two of his bats could see out of the right eye,

just three of them could see out of the left eye,

four could not see out of the left eye,

and five could not see out of the right eye.

He wanted to know the smallest number of bats that he could have examined in order to get these results.

Sources

• 1932: Henry Ernest Dudeney: Puzzles and Curious Problems ... (previous) ... (next): Arithmetical and Algebraical Problems: Various Arithmetical and Algebraical Problems: $147$. -- Blindness in Bats
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Arithmetical and Algebraical Problems: Miscellaneous Puzzles: $219$. Blindness in Bats