2.4 Homework 18th March Answers

Complete neatly in the front of your books. Calculator allowed but working must be shown.

1. A postman has a 12% pay increase from £18,000. What is his new salary? \[£18000\times 1.12 = £20160\]

   [3 marks]

2. The number of insects on a corpse increases by 25% every hour. At 9am there were 1000 insects on the corpse.
   1. How many insects were there at 10am? \[1000 \times 1.25 = 1250 \text{ insects}\]
   2. How many insects were there at 11am? \[1250 \times 1.25 = 1562.5 \mbox{ i.e. 1563 insects}\]
   3. Roughly how many insects will there be by midday? \[1562.5 \times 1.25 = 1953.125 \text{ i.e. 1953 insects}\]

   [6 marks]

3. A pair of trainers costs £35 AFTER a discount of 45%. How much were they before the discount? \[? \times 0.55 = 35 \\ ? = 35 \div 0.55 = £63.64 \]

   [3 marks]

4. A paperboy has his wage increased by 15% to £6.65 per hour. What was his wage before it was increased? \[? \times 1.15 = 6.65 \\ ? = 6.65 \div 1.15 = £5.78 \]
5. Express 490 as a product of its prime factors \[ 490 = 2 \times 5 \times 7^2\]

   [2 marks]

6. How many millimetres are there in 150m? \[150m \times 100 = 15000cm \times 10 = 150,000mm\]

   [2 marks]

7. £1 is worth $1.75
   1. How many dollars is £5.85? \[5.85 \times 1.75 = \$10.24\]
   2. How many pounds is 228? \[228 \div 1.75 = £130.29\]

      [3 marks]