O-LevelMathematicsNumber4024/21 · Oct/Nov 2021 · Q118 Marks

1 (a) In October, Sara is charged $84.25 for water. A tax of 8% is added to this amount. Calculate the total amount Sara is charged for water in October including tax. $ (b) The table shows the rates that Sara is charged for her gas and electricity supply. She is charged a fixed amount each day plus an amount for each unit used. | | Cost for one day | Cost for one unit | | :----------- | :-------------- | :-------------- | | Gas | 23 cents | 4.3 cents | | Electricity | 28 cents | 16 cents | (i) Sara uses a total of 960 units of gas in the 30 days of November. Calculate the total amount, in dollars, Sara is charged for gas in November. $ (ii) Sara is charged a total of $30.80 for electricity in the 30 days of November. Calculate the number of units of electricity she used. units (c) The amount of electricity generated is measured in Gigawatt hours (GWh). The table shows information about the amount of electricity generated in different countries. | Country | Electricity generated in 2010 (GWh) | Electricity generated in 2016 (GWh) | | :-------- | :---------------------------------- | :---------------------------------- | | Australia | 2.37 × 10⁵ | 2.43 × 10⁵ | | Japan | 1.09 × 10⁶ | 1.03 × 10⁶ | | Spain | 2.91 × 10⁵ | 2.64 × 10⁵ | | Turkey | 2.03 × 10⁵ | 2.62 × 10⁵ | (i) Calculate how much more electricity was generated in Japan than in Australia in 2016. Give your answer in standard form. GWh (ii) Calculate the percentage increase in electricity generated in Turkey from 2010 to 2016. % (iii) There was a 4% decrease in the amount of electricity generated in Spain from 2013 to 2016. Calculate the amount of electricity generated in Spain in 2013. GWh

(a)In October, Sara is charged $84.25 for water. A tax of 8% is added to this amount. Calculate the total amount Sara is charged for water in October including tax.[2]
(b)(i)Sara uses a total of 960 units of gas in the 30 days of November. Calculate the total amount, in dollars, Sara is charged for gas in November.[2]
(b)(ii)Sara is charged a total of $30.80 for electricity in the 30 days of November. Calculate the number of units of electricity she used.[3]
(c)(i)Calculate how much more electricity was generated in Japan than in Australia in 2016. Give your answer in standard form.[1]
(c)(ii)Calculate the percentage increase in electricity generated in Turkey from 2010 to 2016.[2]
(c)(iii)There was a 4% decrease in the amount of electricity generated in Spain from 2013 to 2016. Calculate the amount of electricity generated in Spain in 2013.[2]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.

[2] (a) 90.99
[2] M1 for 84.25 + 8/100 × 84.25 oe or B1 for 6.74
[2] (b)(i) 48.18 final answer
[2] M1 for 960 × 4.3 + 30 × 23 or 960 × 0.043 + 30 × 0.23
[2] If 0 scored, SC1 for answer 222.09
[3] (b)(ii) 140
[3] M1 for 3080 – 30 × 28 oe or 30.8 – 30 × 0.28 oe
[3] M1 for their 2240 ÷ 16 oe
[1] (c)(i) 7.87 × 10⁵ final answer
[2] (c)(ii) 29.1 or 29.06...
[2] M1 for (2.62×10⁵-2.03×10⁵) / 2.03×10⁵ [×100] oe or for 2.62×10⁵ / 2.03×10⁵ - ×100 oe
[2] (c)(iii) 275 000 or 2.75 × 10⁵ nfww
[2] M1 for (100-4)/100 x = 2.64×10⁵ soi

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