If there were 200 students who passed an English course three years ago, and each subsequent year until the current one that number increased by 50% of the previous year's number, how many students will pass the course this year?
Think hard. Detailed solution:
675
We begin 3 years ago with 200 students, and moving forward to two years ago we find there were 200 * 1.

5 = 300 students who passed.

At the end of the subsequent year 50% more students pass than last year's 300, so that means 300 * 1.

5 = 450 students pass.

At the end of the current year there's another 50% increase over the previous year, meaning we have 450 * 1.

5 = 675 students pass.

.

The final answer: 675