Abag contains only red and blue marbles. yasmine takes one marble at random from the bag. the probability that she takes a red marble is 1 in 5. yasmine returns the marble to the bag and adds five more red marbles to the bag. the probability that she takes one red marble at random is now 1 in 3. how many red marbles were originally in the bag?

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204