If two students, Mark and Lisa, interchange their ranks in a group of 40, where Mark is 10th from the top and Lisa is 15th from the bottom, what will be Mark's new rank from the bottom after the interchange?
Answer: A. 26th
After the interchange, Mark's new rank from the bottom is calculated as 40 - 10 + 1 = 31. Since Lisa was 15th from the bottom, Mark becomes 26th from the bottom.