+196 You are standing on a sidewalk and watching a parade pass by. Here are the observations you make:
1. For the first 7 minutes, 50 people walk by you per minute.
2. This rate decreases by 20% for the next 3 minutes.
3. This rate decreases by 50% for the next 2 minutes.
How many people passed by you?
+23253 1) For the first 7 minutes, 50 x 7 = 350 persons walked by you.
2) Since the rate decreased by 20%, only 80% as many persons walked passed (per minute) the next 3 minutes.
0.80 x 50 = 40 persons per minute
40 x 3 = 120 persons.
3) Now, does the phrase "this rate" refer to the rate of part #1, or the rate of part #2?
If it refers to part #1, 50% of 50 is 25 persons per minute.
25 x 2 = 50 persons for a total of 350 + 120 + 50 = 520 persons.
If it refers to part #2, 50% of 40 is 20 persons per minute.
20 x 2 = 40 persons for a total of 350 + 120 + 40 = 510 persons.
