Grade 9 Logic Problems Worksheet
Engage grade 9 students with a challenging set of logic problems designed to enhance critical thinking and problem-solving skills.
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Grade 9 Logic Problems
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Read each logic problem carefully and use your reasoning skills to find the correct answer. Show your work or explain your thought process for each problem.
1. You are on an island inhabited by two types of people: Knights, who always tell the truth, and Knaves, who always lie. You meet two islanders, A and B. A says, "B is a Knight." B says, "We are of opposite types." What are A and B?
2. You are in a room with three light switches, each connected to one of three light bulbs in an adjacent room. You cannot see the light bulbs from the room with the switches. How can you determine which switch controls which bulb by only entering the room with the bulbs once? Explain your strategy below.
My strategy: First, I will turn on switch 1 and leave it on for a few minutes. Then, I will turn off switch 1 and turn on switch 2. Immediately after turning on switch 2, I will enter the room with the light bulbs. Upon entering, I will observe the following: the bulb that is currently lit is controlled by switch . The bulb that is off but warm to the touch is controlled by switch . Finally, the bulb that is off and cold is controlled by switch .
3. A farmer needs to cross a river with a fox, a goose, and a bag of corn. The boat can only carry the farmer and one other item at a time. If left alone, the fox will eat the goose, and the goose will eat the corn. How can the farmer get all three across the river safely?
Take the fox, return, take the corn, return with the fox, take the goose, return, take the fox.
Take the goose, return, take the fox, return with the goose, take the corn, return, take the goose.
Take the corn, return, take the fox, return with the corn, take the goose, return, take the corn.
All of the above are incorrect.
4. You have a box that weighs exactly 10 kg. If you add 5 kg of sand to it, the box will now weigh exactly 15 kg. True or False?
True
False
5. In a drawer, there are 10 red socks and 10 blue socks. If you are blindfolded, what is the minimum number of socks you must pull out to guarantee you have a matching pair?