Author: admin

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Impossible maths problem? Not so hard!

Here is an interesting article on a maths question many Australian High School students were complaining about. I think that the question is rather contrived and therefore I would have avoided setting it. It’s not totally impossible though. It relies on knowledge that the median is the middle line in the box plot so that the mean can be calculated. Now you also need to calculate the regression line gradient so that requires knowing a point on the graph. This point is therefore (22 – 0.525, 684/20) i.e. (mean of x, mean of y).

b is therefore 2.0864 and using a value of x = 19, we find that y = -10.6063 + 2.0864 x 19 = 29 chirps per minute (to the nearest whole number).

https://interestingengineering.com/high-school-cricket-math-question-stumps-the-internet

If you are looking at ways to improve your understanding of mathematics, I can recommend some resources.

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How gravity works, a mysterious force.

Isaac Newton was the first person to grasp the significance of gravity as a universal force. He realised that the same force that caused an apple to fall from a tree caused the planets to orbit the sun. He understood its nature and how it could predict the shapes of the orbits of the planets and how they moved – Kepler’s Laws of planetary motion.

Gravity is a mystery. It obeys the inverse square law just like the electrostatic force does however it cannot be shielded unlike the electrostatic force. Imagine a charged particle. It is attracted to (or repelled by) another charged particle placed in its vicinity. However if a conducting plate is placed in between the two, there will be no influence of one charge on the other extended beyond the conducting plate. However it is impossible to shield gravity in the same way.

A great explanation of how gravity works

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The science of camouflage.

In this video, an artist paints people to make them appear two dimensional. Art is being used as camouflage. Animals in the wild do this too of course. Zebras have their stripes, leopards have spots and some animals like the chameleon can even change the patterning on their body to fit the environment. The argument for how zebras’ stripes benefit them is that the hunter finds it difficult to distinguish an individual animal from the herd. In some cases, camouflage works differently, helping animals to blend into their surroundings when viewed from a distance.

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Single use plastics are a scourge

At current estimates, only 9% of the world’s plastic production is recycled.

Just imagine – sixty years ago, there was hardly any plastic production and of the estimated 40 million tonnes produced annually, a tiny proportion is recycled. The only true solution to the plastics problem is to stop using non-biodegradable plastic altogether. There are many interesting and novel approaches to cleaning up our planet from plastic waste but the most obvious way is to avoid putting plastic waste out there in the first place.

This Yorkshire scientist is looking at ways to help dentists cut down on single use plastics.

https://www.bbc.co.uk/news/av/uk-england-south-yorkshire-49528007

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Bitcoin is unpredictable

There are so many articles on Bitcoin these days. It’s going up, no down, hang on I meant up. The problem is that no-one really understands it. Maybe an investor got lucky and made a lot of money but that does not make them an expert on the matter.

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Save My exams – recommended resource

Save My Exams

https://www.savemyexams.co.uk/

I highly recommend this resource for mathematics revision. This is the site I use the most. There is much material available for free, including much syllabus-specific material on the new A-level. Many of the mark schemes are available for the subscription of £60 per year. It is regularly updated.

I am always impressed at the people who spend so much time creating such sites. They really do dedicate a lot of time to them.

Another great site is Physicsandmathstutor.com. It is free to use and has a host of GCSE and A-Levél material. Many students use this. You may also view my page where I list various resources here.

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GCSE results: girls fare better than boys under more rigorous courses

Examination results

I think it is because boys tend to be more laid-back and don’t like to show their working. In recent years, with the introduction of the grades 1 – 9 to replace the letter grades, exams have become more rigorous to combat grade inflation.

More than one in four exam entries by girls aged 16 received top grades of A or 7 and above in this summer’s exams in England, Wales and Northern Ireland, an improvement of half a percentage point to 25.3% compared with last year, while just 18.6% of entries by boys in Year 11 achieved the same grades.

Guardian Education 22nd August 2019

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