Multiple choice

A box contains 20 defective items and 80 non-defective items. If two items are selected at random without replacement, what will be the probability that both items are defective?

  1. $\frac{1}{5}$
  2. $\frac{1}{25}$
  3. $\frac{20}{99}$
  4. $\frac{19}{495}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$=\frac{\frac{20\times19}{2}}{\frac{100\times99}{2}}=\frac{19}{495}$

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