Algebra PlayClass 8 Mathematics Case Study Questions
10 Questions
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Case 1 of 10
Case Study7 marks
The School Fair Game Stall
Rohan is setting up a 'Mind Reader' game stall for his school fair. The game involves a series of mathematical steps that a participant must follow. Rohan claims he can predict the final answer, no matter what number the participant starts with. He has designed a simple trick to attract the younger students. The instructions are:
- Think of any whole number.
- Multiply it by 3.
- Add 15 to the result.
- Divide the new result by 3.
- Finally, subtract the original number you thought of.
Rohan confidently tells every participant that their final answer will be a specific number. He wants to analyze the trick using algebra to be sure it always works and to think about how to create new, more complex tricks for the fair.
Questions on this case
1(1 mark)MCQ
If a participant thinks of the number , what is the algebraic expression after completing the first three steps (multiply by 3, then add 15)?
2(1 mark)
What is the final number Rohan will always predict?
3(1 mark)
If a participant starts with the number 20, what is their result after step 4 (dividing by 3)?
4(2 marks)MCQ
Rohan wants to change the trick so the final answer is always 8. Which of these changes to step 3 ('Add 15') would work?
5(2 marks)
Create a new 4-step trick using multiplication, addition, division, and subtraction that always results in the number 10.
Case Study7 marks
The Birthday Party Magician
A magician is hired for a birthday party. He performs a math trick to guess a guest's birth date. He asks a volunteer, Priya, to perform a series of calculations quietly and only tell him the final result. The instructions are as follows:
- Take the number of your birth month (January=1, February=2, etc.).
- Multiply it by 5.
- Add 6 to the result.
- Multiply the entire sum by 4.
- Add 9 to this result.
- Multiply the new result by 5.
- Finally, add your birth day number to this total.
Priya follows the steps and tells the magician her final answer is 788. The magician correctly guesses her birthday. We can use algebra to understand how he did it.
Questions on this case
1(1 mark)MCQ
If Priya's birth month is , what is the algebraic expression after the first 3 steps?
2(2 marks)
Let the birth month be and the day be . Find the final algebraic expression for the result after all 7 steps.
3(1 mark)MCQ
Priya's final answer was 788. To find her birthday, the magician first subtracts a specific number from 788. What is this number he subtracts?
4(2 marks)
What is Priya's birthday (Month and Day)?
5(1 mark)
Another guest, Arjun, has his birthday on March 15th. What final number will he tell the magician after following all the steps?
Case Study7 marks
Calendar Garden Plots
A school's eco-club is designing a vegetable garden. The garden is laid out in a large grid, similar to a calendar month. To make planning easier, they are selecting square sections for different types of plants. A student, Aisha, observes a pattern. She considers a square of dates from a calendar page. Let's say the top-left date in this square is represented by the variable . The numbers in a calendar grid increase by 1 as you move to the right and by 7 as you move down a row. Aisha tells her teacher that if she knows the sum of the four numbers in any square, she can identify all the dates in it. For example, she is told the sum of four dates in a square plot is 60.
Questions on this case
1(1 mark)MCQ
If the top-left number in the grid is , which expression represents the number in the bottom-right corner?
2(2 marks)
Write the algebraic expression for the sum of all four numbers in the grid in terms of .
3(2 marks)
If the sum of the four numbers in a square is 60, what is the value of the top-left number, ?
4(2 marks)
For the plot where the sum is 60, what are the four dates in the square plot?