Has someone studied the Rates chapter of the Manhattan Guide?, Is it useful?
I have read it very fast and I think that makes this topic complicated, while it is very simple.
I think that it is just important to know some basic formulas. Period. However, they use charts that I have never used in my life!
Please, give me your feedback to confirm whether I should study or skip it.
You need to know only two things to solve any rates problem:
1. Rates are additive (not time) - e.g. if A's speed is 1/2 work per hr and B's speed is 1/3 work per hr, together they do (1/2 + 1/3) work per hr.
Instead if we know that A does the work in 2 hrs and B does it in 3 hrs, they DO NOT take 5 hrs together! (obviously!)
2. Work = Rate*Time
If they do 1 work, then Rate is inverse of time (Say if A takes 3 hrs to complete a work, his rate is 1/3)
If they are working together, use their combined rate in the formula (since you can add rates)
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