This is the Math Kangaroo Solutions video library, presenting solution suggestions for levels 1 and 2 from the year 2016. These solutions are presented by Agata Ghazal. The purpose of the Math Kangaroo Solutions video library is to help you learn how to solve math problems such as those presented in the Math Kangaroo competition. Let me start with a few tips of how to best utilize these solutions. First, make sure that you read the problem, and in this case, listen to it carefully. This will help you understand what kind of information you need to solve the problem. After reading the problem, I will wait for a few seconds. Please use this opportunity to pause the video and try solving the problem on your own. If you get stuck, don't worry. I will start the presentation of the solution with a hint of how to arrive at the correct answer. You can pause the video again at this point and try to finish the problem. My presentation of the solution will follow. Keep in mind that there might be ways of solving the problem other than what I present. I hope that you will learn something new from each problem you attempt, and most importantly, that you will have fun. Problem 1. Which letter on the board is not in the word koala? Our options are R, L, K, N, or O. It's easiest to figure it out if you see which letters are actually shown on the board. Looking at the board, we see that there are only four letters listed there. We see an A. There are several A's. Let's mark them all off. Another letter that we see is O. And the only letter that's left there is N. Now of these letters, only the letter N is not part of the word koala. Remember, we spell koala as K-O-A-L-A. So the letter that is on the board but is not in the word koala is the letter N. So you should choose answer D, which is the letter N. Problem number 2. How many ropes are there in the picture? For our answer, we have the choices of 2, 3, 4, 5, or 6 ropes. A good way to try to solve this problem is to look at the ends and see where the ropes begin and end, and thus figure out how many ropes there are. I will go ahead and color each of the ropes a different color. Start with this one, make it in blue, loops around here, continues here, and there we go. And there's its end. Let's see where this end will take us. Purple rope goes through here and ends right there. And then, let's make a green rope from here. Let's follow them around. Another curve, and it ends here. So we can see that there are 3 ropes, which I marked with blue, green, and purple. So our answer is B, 3 ropes. Michael built a house using matches as shown in the picture. How many matches did he use? Our choices for the answers are 19, 18, 17, 15, or 13 matches. Each match will look like this. To solve this problem, I will mark each match as we count it in the picture. Here's 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 matches. That takes care of all of them. So there are 15 matches in the picture, so Michael used 15 matches to build his house. Problem number 4. In a cave, there were only 2 seahorses, 1 starfish, and 3 turtles. Later, 5 seahorses, 3 starfish, and 4 turtles joined them. How many sea animals gathered in the cave? Our answer choices are 6, 9, 12, 15, or 18. To solve this problem, first we need to see how many animals were in the cave at the beginning, and then how many joined them, and add these two numbers together. We are told that at the beginning, there were 2 seahorses, 1 starfish, and 3 turtles, which is 6 animals. And here they are. Later, there also came 5 more seahorses, and 3 more starfish, and 4 turtles, which is 5 plus 3 is 8, plus 4 will be 12. And here are these animals. So together, we have 6 plus 12 animals, I'll write it as 12, plus 6, which is 18. We can also just count the pictures of the animals. So the correct answer is E. 18 animals were in the cave. Problem number 5. Which point of the labyrinth can we reach starting from point O? The best thing to do in this problem is to draw a path from point O and try to connect to one of the other points. I will draw a path from point O and see which point I can reach. We can also see that there are walls which block off point O and point C from any of the other points in the picture. So the only point that you can reach from point O is point C. So the answer is C. Problem number 6. 10 friends came to John's birthday party. 6 of them were girls. How many boys were at the party? Our choices are 4, 5, 6, 7 or 8. Hint, remember that John is also a boy. Here is John. Now we need to add the 10 guests. 6 of them are girls. 1, 2, 3, 4, 5, and 6. Now, since there are 10 guests, and 6 of them were girls, then 4 of the guests are boys. And here they are. To find the total number of boys at the party, we will add John, that's 1, and the number of guests who are boys, which is 4. 1 plus 4 is 5. So our answer is B, 5. Problem number 7. On a certain street, the houses are numbered 1, 2, 3, 4, and so on. Matt had to deliver flyers about recycling to all houses numbered from 25 to 57. How many houses got the flyers? In a problem like this, it's sometimes a good idea to make a simpler problem to figure out a pattern that can help us solve the final problem. Let's think how many houses there would be if Matt had to deliver flyers to houses numbered from 25 to 27. Now, we know that 27 minus 25 is 2. But are there 2 houses? So here are the houses numbered 25 through 27. And we see that there are 3 of them. So instead of 2, there will be 3. What if the houses were numbered through 28? There would be 4 instead of 3. When up to 29, there would be 5 instead of 4, which is the difference between 29 to 25. We see that we need to add 1 to the difference between the number of the last house and the number of the first house to get the number of houses. Now we can perform our final calculations. 57 minus 25 is 32. However, we need to add 1 more to get the number of houses. 32 plus 1 is 33. So the answer is C. Matt had to deliver flyers to 33 houses. Problem number 8. Which shape can we make using 10 cubes? Hint, there might be cubes that we can't see that are supporting cubes above the first layer. Figure A is the figure which we can make using 10 cubes. Let's look at it more closely. We can see that on the bottom layer, there are 1, 2, 3, 4, 5 cubes that we can see. Also, we need to remember that there are 2 cubes hidden because something needs to be supporting this column and this column. So there are 2 hidden cubes on the bottom layer plus 2 more cubes on the second layer plus 1 more on top. 5 plus 2 plus 2 plus 1 is 10. So our answer is A. You can go through and the same way count the cubes and all the other answers. Remembering that wherever you see a column sticking out above the first layer, there is something underneath supporting it.

Math Kangaroo

problem-solving

Agata Ghazal

video library

learning strategies