Linear Equations for Common Admission Test (India) This question from linear equations is a question which has appeared in common admission test which is conducted in India for admission into postgraduate management programmes of premier management institutes of the country. A box contains 5 apples, 7 oranges and 11 pineapples. At least how many fruits should one pick to have at least 4 fruits of the same kind? A) 9 B) 10 C) 11 D) 12 # LinearEquation

The answer is $10$ and I don't see what this has to do with linear algebra.

$9$ is not enough because it could be that you picked $3$ of each fruit.

However $10$ is enough. If by contradiction you picked $10$ fruits yet you didn't pick $4$ of any given fruit then you must've only picked up to $3$ of each but then you only picked up to $9$ fruits by contradiction.