How I stopped an Alien Invasion using Proportion

When I got home from school, I had noticed that their was an oddly shaped vehicle parked in our backyard that turned out to be a UFO. I ran inside the house and found my parents tied to a chair and beside them were aliens. They told me that if I didn't solve three proportional questions, they would take my parents to their planet and blow up the earth. I had no choice but to obey them.

The first question I had to solve was:

21. David can saw a log into three pieces in 7 min. If he continues sawing at a constant rate, how long will it take him to saw a similar log into six pieces?


It will take David 14 minutes to saw a similar log into 6 pieces. I got 14 by multiplying 3 pieces by 2 to get 6 pieces and what you do to one side you to the other so I multiplied 7 min. by 2 to get 14 min.


They told me that this was just the start and it will get harder.



The second problem was:

20. A breakfast cereal contains corn, wheat, and rice in the ratio of 3 to 4 to 2. If a box of cereal contains 225 g of corn, how much rice does it contain?


The box of cereal will contain 150 g of rice. A breakfast cereal contains corn, wheat, and rice in the ratio of 3 to 4 to 2. I took 3 from the ratio and multiplied it by 75 because a box of cereal contains 225 g of corn and to get from 3 to 225 you multiply by 75. To figure out how much rice the cereal contains, I took 2 from the ratio and multiplied it by 75 to get 150 g of rice.


They were starting to worry that their plan of blowing up the earth was not going to happen. I had answered two questions correctly, now it's time for the last question.



The last question was:

14. Last night 30 cm of snow fell in 6 h. If it continues snowing at the same rate, how long will it take for 45 cm of snow to fall? Determine the answer two different ways.


It will take 9 hours for 45 cm of snow to fall. I got that by multiplying 30 cm by 1.5 to get 45 cm. I also multiplied 6 hours by 1.5 to get 9 hours.

Eventually I was able to solve the problems without having much trouble. They finally let my parents free and left the earth without blowing it up.