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The probability of obtaining heads on a biased coin is 0.4. The coin is tossed 600 times. Write down the mean number of heads and the standard deviation of the number of heads.

The distribution of heads on a biased coin will be binomial - there are only two possible outcomes for a given throw (disregarding the coin standing upright after a toss). Thus X ~ B(600, 0.4) - where X i...

Answered by Aleksander L. • Maths tutor

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Solve x^2 – 6x – 8 = 0 Write your answer in the form a ± √ b where a and b are integers. (Higher tier paper)

To solve this equation we cant use the PSF method, as nothing multiplies to -8 and adds to -6. (Also in the question it says the answer will be in a±b which is normally what you get when you can't factori...

Answered by Alex D. • Maths tutor

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Solve the simultaneous equations 2x - y = 13, x - 2y = 11

In order to solve simultaneous equations, you need to make either terms of x (i.e. '2x') or terms of y (i.e. 'y') in equation (1) and equation (2) equal. To do this, multiply either (1) or (2) as sh...

Answered by Graciella M. • Maths tutor

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