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15C Worked Solutions

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EdTechonGC Mallett
EdTechonGC Mallett

Little Red Riding Hood needs to cross 7 bridges, each with a troll that takes half her cakes but gives one back. Working backwards, she would need to start with 2 cakes to arrive with exactly 2 cakes. An octahedral die has probabilities of 1/8 for 3, 1/2 for 1-4, 1/4 for 7 or more, and 5/8 for 5 or less. If a circle with radius 5m has the same area as a square, the width of the square is 8.86m.

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Exercise 15C – WORKED SOLUTIONS Question 1 Little Red Riding Hood is going to visit her grandma. This time, there is no wolf to bother her on her walk. However, she does need to cross 7 bridges, and under each bridge there lurks an evil troll. Each troll insists that she hand over half of her cakes, but then gives her back one. How many cakes does she need to start with if she wants to arrive with exactly 2 cakes? Working Backwards 7th bridge = Finishes with 2 after getting one back (therefore, before this, she had 1 cake and (2 – 1) and having twice as many before that (2 x 1), leaving 2. This pattern will continue indefinitely.. Therefore, Little Red Riding Hood would need to start with 2 cakes. Question 7 An octahedral die has eight faces with the digits (1 to 8) on them. What is the probability of rolling: a. 3? 1/8th b. 1 to 4? 4/8th = 50% or 1/2 c. 7 or more? ¼ or 25% d. 5 or less? 5/8ths
Exercise 15C – WORKED SOLUTIONS Question 10 A circle and a square have the same area. The circle has the radius of 5 m. What is the width of the square? π r2 = l ×w 3.14× 52 Area of square and circle = 78.5 78.5 = 8.86 Because the width and length are the same, you just needed to find the square root of 78.5. Therefore, the width is the same as the length and the length of both = 8.86m

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15C Worked Solutions

  • 1. Exercise 15C – WORKED SOLUTIONS Question 1 Little Red Riding Hood is going to visit her grandma. This time, there is no wolf to bother her on her walk. However, she does need to cross 7 bridges, and under each bridge there lurks an evil troll. Each troll insists that she hand over half of her cakes, but then gives her back one. How many cakes does she need to start with if she wants to arrive with exactly 2 cakes? Working Backwards 7th bridge = Finishes with 2 after getting one back (therefore, before this, she had 1 cake and (2 – 1) and having twice as many before that (2 x 1), leaving 2. This pattern will continue indefinitely.. Therefore, Little Red Riding Hood would need to start with 2 cakes. Question 7 An octahedral die has eight faces with the digits (1 to 8) on them. What is the probability of rolling: a. 3? 1/8th b. 1 to 4? 4/8th = 50% or 1/2 c. 7 or more? ¼ or 25% d. 5 or less? 5/8ths
  • 2. Exercise 15C – WORKED SOLUTIONS Question 10 A circle and a square have the same area. The circle has the radius of 5 m. What is the width of the square? Ï€ r2 = l ×w 3.14× 52 Area of square and circle = 78.5 78.5 = 8.86 Because the width and length are the same, you just needed to find the square root of 78.5. Therefore, the width is the same as the length and the length of both = 8.86m