Guinea Pig Fractions

These math problems are centered around a guinea pig, who, in his adventures, gets fed, gets fed more, bites his owner, gets put on a diet, swallows a balloon, and runs around.

You decided it’s time to feed your guinea pig. He needs 5/9 of an ounce of carrots, 3/5 of an ounce of celery, and 2/3 of an ounce of parsley. You wonder, “How much food is that?” So you set up a math problem: 5/9 + 3/5 + 2/3. But you don’t know how to add that. Well, here’s how you do it. First, find the LCD (Least Common Denominator) and multiply the top and bottom by the same number, so the bottom number matches the LCD. You should see that your LCD = 9 x 5 = 45.  So then you need to multiply your first fraction by 5/5, your second fraction by 9/9 and your third fraction by 15/15. Now, your math problem should look like this: 25/45 + 27/45 + 30/45. Then, add the fractions, keeping the bottom number the same. Your sum should be 82/45. The last step is to reduce the fraction and take the wholes out. Your sum should be 1 37/45. You can’t reduce that because 37 is prime.

Your guinea pig has grown. He now eats 1 2/3 of an ounce carrots, 2 1/12 of an ounce celery, 1 1/4 of an ounce parsley. How much food is that? Your math problem should look like this: 1 8/12 + 2 1/12 + 1 3/12. But what do you do with the whole numbers? Just add them separately. Your sum should be 4 12/12 ounces. 12/12 equals 1 and add 4 to get 5.

Your guinea pig has been biting you. The first time he did it, you took 4/9 of an ounce of his food away. The next time he did it, you took 5/9 of an ounce away. How much food have you taken out? First, take 4/9 from 5. To do that, take one whole out of 5 and display it as 9/9 because the denominator of the fraction you are subtracting is 9. Your math problem should end up like this: 4 9/9 - 4/9 = 4 5/9 ounces of food. Now take 5/9 away from that for the second time he bit you. Your math problem should end like this: 4 5/9 - 5/9 = 4 ounces of food.

Your guinea pig has been so mean that you decided to put him on a more strict diet. Your guinea pig is not happy about it. You are trying to convince him that he has enough food. 3 4/5 ounces is how much you feed him now and 4 ounces is how much you used to feed him. Compare 4 and 3 4/5. Your math problem should look like this: 4 - 3 4/5. But you can’t figure out how to take 4/5 from nothing. We’ll, here’s how to do it. First, turn 4 into 3 5/5 because the denominator of the fraction you are subtracting is 5. Your math problem should look like this: 3 5/5 - 3 4/5. Now subtract starting with the whole numbers. 3 - 3 = 0. Then the fractions 5/5 - 4/5 = 1/5. 1/5 of an ounce is how much you took away. You show this to your guinea pig and say, “I haven’t taken that much food away!” Your guinea pig glares at you.

Your guinea pig swallowed a balloon and freaked out, hyperventilating. The balloon filled with air and floated up in the air, with the guinea pig wrapped around it. The balloon flew 5 times as high as the guinea pig could jump ( which was 3/4 of an inch ) in one second. How high did the guinea pig go? To do this math problem, we need to put a 1 under the 5, which is the fraction equivalent of 5. Your math problem should look like this: 5/1 x 3/4 inch. Since there are no common factors, multiply straight across the numerators and denominators (5x3 over 1x4) to get 15/4 inch. Turn the improper fraction into a mixed number, which equals your final answer, 3 3/4 inch.

In the next two seconds, your guinea flies 1 1/2 times farther. How high did he travel? To do this problem, turn 1 1/2 into a improper fraction by multiplying 1 x 2 to get 2. Add 2 to the numerator to get 3/2. Your problem should look like this 3/2 x 15/4. There are no common factors, so multiply straight across to get 45/8 which becomes your final answer, 5 5/8. The numerator 5 is prime, so it can’t reduce.

Your guinea pig looked so hungry when he ate the balloon, so you decide to feed him his full five ounces of food. He’s so happy when he sees the food that he does a victory dance and has some friends come so they can share the prize.

The three guinea pigs were sharing 1/2 a carrot, but they couldn’t agree how much carrot they should each get. What is 1/2 divided by 3? To do this problem, stick a 1 under the 3 to get 3/1. Your problem should look like this: 1/2 divided by 3/1. Next, flip 3/1 upside down and change divided by to multiply. The math problem should look like this: 1/2 x 1/3. No common factors, so multiply straight across to get 1/6 of a carrot.

Then, some more guinea pigs came over. 5 guinea pigs were now trying to share 1 2/3 of an ounce of celery. How much celery does each guinea pig get? To do this problem start with this: 1 2/3 divided by 5/1. Next, flip 5/1 and replace divided by with multiply by. Now your problem should look like this: 1 2/3 x 1/5. Now turn 1 2/3 into an improper fraction by multiplying 3x1 and adding it to numerator to get 5/3. Your problem now looks like this: 5/3 x 1/5. Both 5’s cancel to get 1/3 x 1/1.  Now, multiply straight across to get 1/3 of an ounce.

The 5 guinea pigs had one 4 ounce carrot. How many ounces of carrot is that? To do this math problem, start with what you have, which is 5 guinea pigs. Then, write the units you want in the end, after the equals sign.  Here, we want ounces of carrot. Now  multiply by your conversion factor so that the units you do not want go away.  Your problem now looks like this: ( 5 guinea pigs) ( 4 ounce carrot / 1 guinea pig) = ? ounces of carrots.   Cross off both “Guinea pigs”. Your problem should look like this: (5) (4 ounce carrot / 1) =    ounces of carrot. This tells you to multiply 4x5 to get 20 ounces of carrot.

There was 16 ounces of parsley and each guinea pig got 4 ounces of it. How many guinea pigs did it take to finish the parsley? To do this problem, start with what you have, which is 16 ounces. Then, write the units you want in the end, right after the equals sign. Here we want the number of guinea pigs. Now multiply by your conversion factor so that the units you do not want go away.  Your problem should look like this: ( 16 ounces) ( 1 guinea pig / 4 ounces) =   number of guinea pigs. Cross off both “ounces”.  Your problem should look like this: (16) (1 guinea pig / 4) =   number of guinea pigs. This tells you to divide 16 by 4 to get 4 guinea pigs.

Guinea pigs can be nasty. But if you give them enough food, they can be very happy!