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:
  1. Think of any whole number.
  2. Multiply it by 3.
  3. Add 15 to the result.
  4. Divide the new result by 3.
  5. 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
If a participant thinks of the number xx, what is the algebraic expression after completing the first three steps (multiply by 3, then add 15)?
(1 mark)MCQ
2
What is the final number Rohan will always predict?
(1 mark)
3
If a participant starts with the number 20, what is their result after step 4 (dividing by 3)?
(1 mark)
4
Rohan wants to change the trick so the final answer is always 8. Which of these changes to step 3 ('Add 15') would work?
(2 marks)MCQ
5
Create a new 4-step trick using multiplication, addition, division, and subtraction that always results in the number 10.
(2 marks)