Question 979607
Since you know that there are 85 students who are maths majors out of 800, the probability of being a maths major is {{{85/800}}}. Also, the probability of a student being a computer science major is {{{125/800}}}.
 
To find the probability of a student being both, you must multiply the probability of the events together.
 
{{{85/800  *  125/800 = 17/1024}}}

Therefore the probability of a student being both a maths major and a computer science major is {{{17/1024}}}