7. (6 points) Xiaopang needs 90 seconds to go from the first floor to the third floor. At this speed, it will take him $\qquad$ minutes to go from the second floor to the seventh floor.
【Answer】Solution:
The time to climb each floor is: $90 \div (3-1) = 45$ (seconds); the time it takes for him to go from the second floor to the seventh floor is: $45 \times (7-2) = 225$ (seconds). Answer: It takes him 225 seconds to go from the second floor to the seventh floor. Therefore, the answer is: 225.