14 Problem-solving A circle with radius 5 cm is enlarged by scale factor 3. What is the area of the enlarged circle? 15 STEM / Modelling A group of cells in a Petri dish doubles in area every day. One day the cells cover a roughly circular area of radius 3 mm. a What will the radius of the circular area of cells be the next day? b What will the area of the cells be the next day? 16 Draw a grid with x- and y-axes from −8 to 8. a Plot and join the points (1, 1), (5, 1) and (5, 5) to make a triangle. 1 b Enlarge the triangle by scale factor − 4 with centre of enlargement (−3, −7). 17 Real / Problem-solving A gardener plants a flower bed measuring 3 m by 4 m. For each square metre he needs 30 bulbs. Bulbs come in bags of 50 and cost £6.99 per bag. a What is the cost of bulbs for this flower bed? Another flower bed is 3 times as long and 3 times as wide. b How many bulbs will he need for this flowerbed? c What is the cost of bulbs for this flowerbed? It takes him 4 hours to plant the bulbs in the flowerbed measuring 3 m by 4 m. d How long will it take him to plant the bulbs in the larger flowerbed? 18 A cuboid has surface area 77.5 m2 and volume 43.75 m3. The cuboid is enlarged by scale factor 2.5. Work out a the surface area of the new cuboid b the volume of the new cuboid. Give your answers to 3 significant figures. 19 Problem-solving Sian needs 15 ml of paint for a model of a ship. She makes another model enlarged by scale factor 4. How much paint does she need for the new model? Q20 hint You need to give the scale factor and the centre of enlargement. 20 Problem-solving Describe the enlargement of each red object to its blue image. y 5 b y 5 c y 5 4 4 4 3 3 3 2 2 2 1 1 1 25 24 23 22 210 21 1 2 3 4 5 x 25 24 23 22 210 21 1 2 3 4 5 x 25 24 23 22 210 21 22 22 22 23 23 23 24 24 24 25 25 25 21 Reflect Look back at the questions you answered in these extend lessons. They were all about transformations. List all the other mathematics topics you used to answer these questions. Beside each one, write the type of transformation you used it for. 1 2 3 4 5 x Reflect a Unit 5 Transformations 126