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Nov24

# Problems Involving the Inverse Rule of 3

In this entry, we’re going to look at some problems involving the inverse rule of 3 so you can practice it at home.

If you want to remind yourself of when you should apply the inverse rule of 3 and how to solve it, you can go to this previous blog entry:

Once you’re up to speed on the inverse rule of 3, take a look at the following problems.

### Inverse Rule of 3 Problem 1

In the Great Sea Hotel, there are 3 gardeners during the winter. Between them, they water and tend to all the gardens in the hotel in 6 hours. If there are 3 more gardeners during the summer, how long will it take them to water and tend to all the gardens in the hotel?

To solve this problem, we first have to add the 3 new gardeners to the previous 3. If the 3 gardeners take 6 hours in the winter, 6 gardeners take “x” hours in the summer.

Once we’ve arranged our formula, we just have to solve it.

SOLUTION: “If 3 gardeners take 6 hours, 6 gardeners take 3 hours”

### Inverse Rule of 3 Problem 2

The Motorcrack Rally team has 15 mechanics that are able to change all the parts on one car in 60 seconds. How many seconds would it take 5 mechanics to do the same job?

To solve this problem, we have to think about the situation in the following way: “if 15 mechanics change one car in 60 seconds,  5 mechanics will take x seconds”.

Once we’ve arranged our formula, we just have to solve it.

SOLUTION: “If 15 mechanics take 60 seconds, 5 mechanics will take 180 seconds”

### Inverse Rule of 3 Problem 3

Some of the players on my football team are going to buy a gift for the coach. At first, 4 of us got together and each of us were going to pay $10, but in the end, there were 8 players in total that put up money for the gift. How much money did each person have to pay? To solve this problem, we have to think about the situation in the following manner: “If 4 players have to pay$10, 8 players would have to pay x dollars“.

Once we’ve arranged our formula, we just have to solve it.

SOLUTION: “If 4 players have to pay $10 each, 8 players have to pay$5 each”

I hope these problems have helped you practice the inverse rule of 3. If you want to keep working on these types of exercises, and many more, register with Smartick and try it for free.

Fun is our brain’s favorite way of learning
Diane Ackerman
Smartick is a fun way to learn math
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