# Maths Methods 1

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## Probability

Probability=number of successful outcomes/total number of outcomes

• Probabilties always add up to 1
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## Relative Frequency

Relative Frequency = number of times event happens/number of times it could happen

e.g. number of times toast lands "jam-side up"/total number of times toast dropped

if lands "jam-side up" 8/10, relative frequency = 0.8

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## Indices

x (power of 0) = 1

x (power of -1) = 1/x

reciprocal of x = 1/x

a (power of m) * a (power of n) = a (power of n + m)

a (power of m) - a (power of n) = a (power of m - n)

(a power of n) power of m * n

a (power of -n) = 1/a (power of n)

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## Recurring decimals and fractions

decimal - fraction

e.g. 0.33333...... = 1/3

e.g. 0.666666.... = 2/3

fraction - decimal

e.g. 1/9 = 1 divided by 9 put in bus stop as 1.0000 / 9

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## Rationalise the denominator

multiply fraction by denominator/denominator

e.g. if you have 1/square root 2

do 1/square root 2 * square root 2/square root 2 = square root 2/2

write example below:

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## Direct and Inverse Proportion

e.g. if y is DIRECTLY proportional to x...

...use pair of values given in the equation y = kx to find...k...k is constant (a fixed number that doesn't change)

substitute into the equation to find any missing values

e.g. if s is INVERSELY proportional to t...

you write: s = k * 1/t

...use the pair of values given to find k and then use what you know to find any missing values

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## Surds

a *   b =   ab

a /    b =    a/b

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## Circles

equation of a circle = x squared + squared = r squared

practice this on MyMaths - algebra, graphs, equations of circles