Answer:
10/40 or a 1 in 4 chance he will grab a red marble
Step-by-step explanation:
You add up all of the marbles;
10+15+15
40
Now you take the number of red marbles are divide it by 40;
10/40
That is your answer.
If that is 54.300 the greatest whole number would be 54 if it is supposed to be 54,300 then it would stay the same and be 54,300
So solve for q
first factor q out of the summation

now, determine what the summation is

its been a while since ive done summations so i dont remember any tricks but that summation is essentially equal to

or factored to be something like this

which i believe there's a formula for
regardless using a calculator, the summation turns out to be 4/3 i think
you should definitely double check this step
so replacing the summation for 4/3, the equation is now
q*(4/3) =8
pretty easy to solve from here
divide 4/3 to both sides to get q
any questions?