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

Problem: a certain business school has 500 students , and the law school at the same university has 800 students . among these students , there are 30 sibling pairs consisting of 1 business student and 1 law student . if 1 student is selected at random from both schools , what is the probability that a sibling pair is selected ?
Options: a ) 3 / 40000 , b ) 3 / 20000 , c ) 3 / 4000 , d ) 9 / 400 , e ) 6 / 130
a

Problem: a dog have birth to 12 puppies , 2 female and 10 male . what is the ratio of the female puppies to the male ?
Options: a ) 1 / 5 , b ) 1 / 6 , c ) 1 / 10 , d ) 2 / 12 , e ) 1 / 8
a

Problem: 210 school students were asked in a survey if they preferred windows or mac brand computers . 60 students claimed that they preferred mac to windows brand computers . one third as many of the students who preferred mac to windows , equally preferred both brands . 90 of the students had no preference . how many of the students in the survey preferred windows to mac brand computers ?
Options: a ) 25 , b ) 40 , c ) 50 , d ) 60 , e ) 75
b