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### Gold Increases by 300%!

February19

This gold chart (source: Kitco.com) appears to show a dramatic – over 300% – increase in the value of gold over a period of just 7 hours on February 15th, 2019.

Students learning Mathematics and Statistics must exercise their detective instincts when viewing data in graphical form and this is an excellent example. Of course, gold only went up by \$US7 – still a significant jump, but the graph makes this increase (of around just 0.5%) look must more spectacular. This technique is often used to boost interest in a product, or to exaggerate sales figures. As H3 Maths has said before, graphs tell a story – but, in this case, it is a short story rather than a long novel.

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#### Post Support

10 x 9 x 8 + (7 + 6) x 5 x 4 x (3 + 2) x 1 = 2020

NCEA Level 2 Algebra Problem. Using the information given, the shaded area = 9, that is:
y(y-8) = 9 –> y.y – 8y – 9 =0
–> (y-9)(y+1) = 0, therefore y = 9 (can’t have a distance of – 1 for the other solution for y)
Using the top and bottom of the rectangle,
x = (y-8)(y+2) = (9-8)(9+2) = 11
but, the left side = (x-4) = 11-4 = 7, but rhs = y+? = 9+?, which is greater than the value of the opp. side??
[I think that the left had side was a mistake and should have read (x+4)?]