### Brain Teasers

# Sneak Thief

A thief has been at work in a classroom. When the pupils return from lunch, 80 percent of them have lost a pencil, 85 percent have lost a pen, 74 percent have lost a ruler, and 68 percent have lost an eraser.

What percentage, at least, must have lost all four items?

What percentage, at least, must have lost all four items?

### Answer

If you assume that there are 100 pupils, then adding the percentages together will give the total number of losses: 80+85+74+68=307. This means that there are 3 losses each for each pupil, with 7 pupils losing all 4 items. Therefore, the smallest percentage of pupils that lost all four items is 7%.Hide Answer Show Answer

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## Comments

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it's ok you have to be good at math to get it.

I've gotta start thinking in formulas, because I got it the long way! Fun stuff!

I did it a different way. Ten or so seconds in my head.

100 - ((100-80) + (100-85) + (100-74) + (100-6) =

100 - (20 + 15 + 26 + 32) =

100 - 93 = 7

100 - ((100-80) + (100-85) + (100-74) + (100-6) =

100 - (20 + 15 + 26 + 32) =

100 - 93 = 7

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