Question 1195462
.
box 1 contains 30 red balls and 70 white balls, 
box 2 contains 50 red balls and 50 white balls , 
box 3 contains 75 red balls and 25 red balls 
the three boxes are all emptied into a large box and a ball is selected at random .
if the selected ball is red what is the probability that it came from box 2?
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<pre>
In all, there are 30+50+75 = 155 red balls in the large box.


Of them, 50 red balls came from box 2.


Therefore, if the selected ball is red, the probability that it came from box 2 is  

    {{{50/155}}} = {{{10/31}}}.    <U>ANSWER</U>
</pre>

Solved.


Thank you for asking.