Question 1174649
.
A teacher has two boxes of pens. Box 1 contains 7 blue pens and 3 black
pens, box 2 contains 2 blue pens and 8 black pens. The probability of
selecting a pen from box 1 is 2
3
and the probability of selecting a pen
from box 2 is 1
3
. If a pen is selected at random what is the probability
that it is from box 1 given that it is black?
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As the post is worded,  printed,  posted and presented,  it  MAKES  no  SENSE.



Indeed, this passage from the post  "The probability of selecting a pen from box  1  is  2/3"  is  NONSENSICAL 

without pointing to which color pen it does relate.



Same the next passage  "the probability of selecting a pen from box  2  is  1/3"  is  NONSENSICAL  due to the same reason.



Since the post makes no sense, the solution makes no sense, too.