ANSWERS CALCULATOR TEST Write down all the steps and calculations you make (even if it s on the calculator). Don t round until the end!

Transcription

1 ANSWERS CALCULATOR TEST Write down all the steps and calculations you make (even if it s on the calculator). Don t round until the end! 1. After an 8% pay rise, Mr Brown s salary was What was his salary before the increase? = 108% Divide by 108 to get 1% so = 1% [1] x 100 = 100% [1] = 100% [1] [3 marks 4] 2. A new house cost but increased in value by 15% each year. Work out its value after 5 years to the nearest 1000 Just use the trusty formula x (1.15) 5 [spotting 1.15 is 100%+15% 1] [Using formula 1] [1] [3 marks 4]

2 3. Use your calculator to work out!"#.!!.!"!!.!" a) Write down all the figures on your calculator display Literally, make the calculation look exactly like the one above on your calculator (the joy of having a scientific calculator with a good display) [2] [2 marks 4] b) Write down you answer in part a) to 3 significant figures 404 [1] [1 mark 4] 4. Mr Appleseed s Supercompost is made by mixing soil, compost and grit in the ratio of 4:3:1 Soil costs 8 per 40kg, compost costs 15 per 25kg and grit costs 12 per 15kg How much profit will be made if 16kg of Supercompost is sold for 10? First work out cost of 1 kg of each thing Soil costs 8 per 40kg = 8/40 = 20p per kg compost costs 15 per 25kg = 15/25 = 60p per kg and grit costs 12 per 15kg = 12/15 = 80p per kg [2] Now the ratio part

3 4+3+1 = 8 parts (Call each part 1kg) so = 16 parts (16kg) [1] soil : compost : grit 8 : 6 : 2 makes 16kg of supercompost So how much are you paying for each component? 8x20p 6x60p 2x80p = 6.80 cost of 16kg [1] You re selling for 10 and it costs 6.80 to make so you make a profit of 3.20 [1] [5 marks 5] 5. Write!"!! as a recurring decimal. Just work it out on your calculator (10 11) Mine shows it with the 2 dots but yours may show Remember this isn t the same as 0.90 (without the dots). That means which is!!" [1] [1 mark B] THIS ISN'T THE END OF THE ANSWERS

4 6. Jane has an annual salary of before tax. She pays no tax on the first 9440 of her income this is her tax free allowance. She pays 20% on any income between 9440 and 32010, and 40% on any income over What percentage of her annual salary does Jane pay in tax? Give your answer to 1 decimal place. You know you ve got more that so you can take off your tax free bit straight away from the and work out the basic rate [1] x 20% = 4514 [1] Next, how much do you have to pay at the higher rate? What's left? [1] x 40% = 5196 [1] Add these together amount paid in tax Now make a fraction - how much tax you paid out of your full earnings:!"#$ = x100 = [1] = 21.6 ( to 1 decimal!"### place) People tried doing this other ways but this is the only correct way % [1] [6 marks 4]

5 7. An iron cube has side length 4cm and iron has a density of 7.9 grams per cm 3 a) work out the mass of the iron cube M Drunk monkey s vodka D V Cover M as you need mass. So you need to calculate D x V First of all find V The volume of the cube 4 x 4 x 4 = 64cm 3 [1] 64 x 7.9 [1] = 505.6g [1] g [3 marks 4] b) A larger iron cube has a mass of 63.2kg. What is the ratio of the side lengths of the smaller and larger cubes? So you need to find the volume of this cube first. Cover the V. Turn the kg into g to match the first cube 63200g [1] Mass/density so 63200/7.9 = 8000cm 3 [1] You can use your cube root button here:! 8000 = 20cm [1] or your brain if you happen to know the answer One side is 20cm (20 x 20 x 20 = 8000) And finally the ratio Small: large 4cm : 20cm 1 : 5 [1] 1 : 5 [4 marks 4]

6 8. Ian makes and sells lobster pots. He sells them for 32 per pot which is 60% profit on the cost of materials. He wants to increase his profits to 88%. How much should Ian start charging for lobster pots? Work out how much the cost of materials is selling price is original + profit so 160% [1] To get the original, divide by 160 x by /160 = 0.20 [1] 0.20 x 100 = 20 Now he wants to increase by 88% so % 88% of 20 (you might have used 20 x 0.88) = Add this to your cost price = [1] [3 marks 5] 9. Ishmael is making some t-shirts. It takes 5m 2 of cotton to make 8 t-shirts. 2m 2 of cotton costs 5.50 How much will it cost Ishmael to buy enough cotton to make 85 t- shirts? 2m 2 of cotton costs m 2 is 2.5 times bigger (5/2 = 2.5) [1] so will cost 5.50 x 2.5 = for 8 t-shirts [1] /8 = per t-shirt [1] x 85 = for 85 t-shirts [1] (you may have worked this out using the amount of cotton but it should still come to the same answer) [4 marks 4]

7 10. The gravitational force, f between two objects is inversely proportional to the square of the distance, d, between them. When d = 100, f= 20 Write an equation connecting f and d and use it to find the value of f when d = 800 Don t panic! Just use the inverse ratio gizmo and follow the system. f!!! f =!!! [1] 20 =!!""! 20 x = k k = [1] so f =!"""""!""! f = [1] f = [3 marks 7]