In this task, you need to provide the correct option for a given problem from the provided options.

[EX Q]: Problem: in 50 l can , milk and water in the ratio of 3 : 1 . if the ratio has made 1 : 3 then the quantity of water that has to be added further is ?
Options: a ) 100 , b ) 120 , c ) 90 , d ) 80 , e ) 70
[EX A]: a

[EX Q]: Problem: the ratio , by volume , of bleach to detergent to water in a certain solution is 2 : 40 : 100 . the solution will be altered so that the ratio of bleach ( b ) to detergent is tripled while the ratio of detergent to water is halved . if the altered solution will contain 300 liters of water , how many liters of detergent will it contain ?
Options: a ) 40 , b ) 60 , c ) 50 , d ) 30 , e ) 70
[EX A]: b

[EX Q]: Problem: an urn contains 10 black and 5 white balls . two balls are drawn from the urn one after the other without replacement . what is the probability that both drawn balls are black ?
Options: a ) 1 / 5 , b ) 3 / 7 , c ) 2 / 5 , d ) 3 / 5 , e ) 2 / 7
[EX A]:
b