EM-2849

Combined events

E Math · Secondary 4 · Hard · Combined events

A box contains 5 red pens and 7 blue pens. Three pens are taken at random one after another without replacement.

Find the probability that the three pens are all red.

$\dfrac{1}{22}$
$\dfrac{1}{6}$
$\dfrac{5}{132}$
$\dfrac{3}{22}$

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