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MathRevolution
What is the standard deviation of 3 products’ prices?

1) The sum of any two prices of these 3 products is $1,000
2) At least one of them is $500

woah..took me 17 seconds to answer :D

2 clearly is not sufficient.

1. basically tells us that the prices are equal, meaning only one thing - SD is equal to zero
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MathRevolution
What is the standard deviation of 3 products’ prices?

1) The sum of any two prices of these 3 products is $1,000
2) At least one of them is $500

The sd measures the deviation of each term from the mean.
If the terms are all the same, then the deviation is 0.

1) The sum of any two prices of these 3 products is $1,000 sufic

3 prices: {$500,500,500} or {$1000,1000,0}, but $0 is not possible since price > 0;

2) At least one of them is $500 insufic

No info about the others.

Ans (A)
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