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Economist GMAT
There were \(r\) red balls and \(y\) yellow balls in a bag. Three red balls and four yellow ones were added to the bag. What is the probability that a yellow ball and then a red ball will be selected if Jerry pulls out 2 balls at random, and puts the first ball back before pulling the second ball?
A. \(\frac{y+4}{y+r+7} \cdot \frac{r+3}{y+r+7}\)
B. \(\frac{y+3}{y+r+7} + \frac{r+4}{y+r+6}\)
C. \(\frac{y+3}{y+r+7} \cdot \frac{r+4}{y+r+6}\)
D. \(\frac{y+3}{y+r+7} \cdot \frac{r+3}{y+r+7}\)
E. \(\frac{y+3}{y+r+7} + \frac{r+3}{y+r+6}\)
OA A
There were \(r\) red balls and \(y\) yellow balls in a bag. Three red balls and four yellow ones were added to the bag. What is the probability that a yellow ball and then a red ball will be selected if Jerry pulls out 2 balls at random, and puts the first ball back before pulling the second ball?
A. \(\frac{y+4}{y+r+7} \cdot \frac{r+3}{y+r+7}\)
B. \(\frac{y+3}{y+r+7} + \frac{r+4}{y+r+6}\)
C. \(\frac{y+3}{y+r+7} \cdot \frac{r+4}{y+r+6}\)
D. \(\frac{y+3}{y+r+7} \cdot \frac{r+3}{y+r+7}\)
E. \(\frac{y+3}{y+r+7} + \frac{r+3}{y+r+6}\)
OA A
