Normal Distribution

A set of reading scores for fourth-grade children has a mean of 25 and a standard deviation of 5. A set of scores for sixth-grade children has a mean of 30 and a standard deviation of 10. Assume that the distributions are normal.

From the previous question, the percentage of fourth-graders who score better than the average sixth-grader would be __________ .
The percentage of the sixth-graders who score worse than the average fourth-grader would be______________ .

I found the Z-scores of these and then used a chart to look up the percentages which were: 15.87% and 48.01%.

The next part of this question is:

Under what conditions would the answers for each blank in the previous question be equal?

I was thinking it would be when they are both at 50% but I don't think that that is the right answer.