Hi ya'll,
There was a problem from the gmatprep test that I wasn't sure about. I got the question right but I'm not too confident if my reasoning was right. Can anyone check my reasoning?
Each of the 25 balls in a certain box is either red, blue or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected will either be white or have an even number painted on it?
1) The probability that the ball will both be white and have an even number painted on it is 0.
2) The probability that the ball will be white minus the probability that the ball will have an even number painted on it is 0.2.
From the data,
r + w + b = 25
each of the r,w, and b balls are numbered from 1 to 10
probabilty of w + probability of even = ?
Matrix
----------odd----------even----------total
w--------- ---------- ---------- w
non-w----- ---------- ---------- 25-w
total----- ---------- ---------- 25
1)to me, the statement implies that all white balls are odd and none are even. We are still missing the number of all even numbered balls. Insufficient
2)probability of w - probability of even = 0.2 Can't function alone to answer the question. Insufficient
from 1 and 2 we can only fill the white-even grid (0), but we don't have the number of white balls or the number of even numbers. Statement 2 is misleading; if we knew how many white balls are in the box, we can use statement 1 and 2 to find the answer ( given number of white/25 - e/25 (don't need to know the number of even numbered balls because it's still out of 25, can leave it unknown) = 0.2). Thus, the answer I chose was E.
What do you guys think?
There was a problem from the gmatprep test that I wasn't sure about. I got the question right but I'm not too confident if my reasoning was right. Can anyone check my reasoning?
Each of the 25 balls in a certain box is either red, blue or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected will either be white or have an even number painted on it?
1) The probability that the ball will both be white and have an even number painted on it is 0.
2) The probability that the ball will be white minus the probability that the ball will have an even number painted on it is 0.2.
From the data,
r + w + b = 25
each of the r,w, and b balls are numbered from 1 to 10
probabilty of w + probability of even = ?
Matrix
----------odd----------even----------total
w--------- ---------- ---------- w
non-w----- ---------- ---------- 25-w
total----- ---------- ---------- 25
1)to me, the statement implies that all white balls are odd and none are even. We are still missing the number of all even numbered balls. Insufficient
2)probability of w - probability of even = 0.2 Can't function alone to answer the question. Insufficient
from 1 and 2 we can only fill the white-even grid (0), but we don't have the number of white balls or the number of even numbers. Statement 2 is misleading; if we knew how many white balls are in the box, we can use statement 1 and 2 to find the answer ( given number of white/25 - e/25 (don't need to know the number of even numbered balls because it's still out of 25, can leave it unknown) = 0.2). Thus, the answer I chose was E.
What do you guys think?
