Question

A box contains lemon and banana, if there are 13 bananas in the box and the probability of selecting 2 bananas from the box is 1/10, then find the number of lemons in the box?

Answer 1

13/(13+x) * 12/(12+x) = 1/10
1560=x^2 +25x + 156
Solutions are x=27 and x=-52
You can’t have negative lemons so
The answer is 27 lemons