Given equation : y=ax^2
Taking a to the other side we have, x^2=(1/a)*y
This equation describes a parabola that opens up.
When a is negative, the focus is on the negative y-axis, therefore, the parabola opens down.
The answer is a. down.
Reduce the fraction using 3
13/15+1/8
13/15=1/5
1/5+1/8
8+5/40
fraction response: 13/40
answer in decimal numbers: 0.325
The answer relies on whether the balls are different or not.
If they are not, which is almost certainly what is intended.
If they are, the perceptive is a bit different. Your
expression gives the likelihood that a particular set of j balls
goes into the last urn and the other n−j balls into the other urns.
But there are (nj) different possible sets of j balls, and each of
them the same probability of being the last insides of the last urn, so the
total probability of completing up with exactly j balls in the last
urn is if the balls are different.
See attached file for the answer.