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The graph below can be used to convert between pounds and kilograms.
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Part a) Write down 44 kilograms in pounds.
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Paulina buys a new fridge.
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The weight of the fridge is 17 stone and 12 pounds.
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Part b) Given that one stone is equal to 14 pounds, work out the weight of Paulina’s fridge in kilograms.
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Our first step when dealing with a graph like this is to work out what each little square represents on the 𝑥- and the 𝑦-axis.
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On the 𝑥-axis, 10 squares represent 10 kilograms.
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Dividing both sides of this by 10 tells us that one square is equal to one kilogram.
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On the 𝑦-axis, 10 little squares is equal to 20 pounds.
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Dividing both sides of this by 10 tells us that one square is equal to two pounds on the 𝑦-axis, as 20 divided by 10 is equal to two.
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The first part of our question asked us to convert 44 kilograms into pounds.
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We draw a vertical line up from 44 until we hit our graph.
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We then draw a horizontal line across to the 𝑦-axis.
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This line is one and a half squares below 100.
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Therefore, 44 kilograms is equal to 97 pounds.
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One and a half squares on the 𝑦-axis would be equal to three pounds, and 100 minus three is equal to 97.
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It is important to note that, in an exam, there will be a small margin for error in this type of question.
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However, we need to be as accurate as we possibly can be.
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It’s often recommended to draw lines in pencil first in case we make a mistake.
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The second part of our question told us that Paulina bought a fridge that weighed 17 stone and 12 pounds.
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As one stone is equal to 14 pounds, then 17 stone would be equal to 17 multiplied by 14 pounds.
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17 multiplied by 14 is equal to 238.
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Therefore, 17 stone is equal to 238 pounds.
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This means that 17 stone and 12 pounds is equal to 250 pounds, as 238 plus 12 is equal to 250.
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Our next step is to try and find 250 pounds on the 𝑦-axis.
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Unfortunately, our scale only goes up to 140.
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This means that we need to find a factor of 250 and then we can scale up our answer.
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One-half of 250 is 125.
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Therefore, we need to draw a horizontal line from 125 pounds.
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Note that 125 is two and a half squares above 120.
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Drawing a line vertically down from this point gives us 56.5 kilograms.
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This is because the line is halfway between the sixth and seventh square after 50.
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We can therefore say that 125 pounds is equal to 56.5 kilograms.
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As 250 is double 125, we need to multiply both sides of this equation by two.
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250 pounds is equal to 113 kilograms, as 56.5 multiplied by two is equal to 113.
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We can therefore say that Paulina’s fridge that weighed 17 stone and 12 pounds is also equal to 113 kilograms.
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Using a conversion graph is a good way to convert between metric and imperial units.
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Kilograms are metric, and pounds are imperial.
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In many exams, we’re also expected to know that 2.2 pounds is equal to one kilogram.
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This can be shown from the graph, as 22 pounds is equal to 10 kilograms.
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And dividing both of these numbers by 10 gives us 2.2 pounds is equal to one kilogram.