Suppose that a class contains 10 boys and 15 girls, and suppose that eight students are to be selected at random from the class without replacement. let x denote the number of boys that are selected, and let y denote the number of girls that are selected. find e(x − y ).

i suppose it should be (y=2x-5)

step-by-step explanation:

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.