# unit 3 maths revision

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### Slide 2

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Contents
Proportion
Direct proportion= when 2 quantities increase and
decrease in the same ratio.
Inverse proportion= when one quantity increases
at the same rate as the other quantity decreases.…read more

### Slide 3

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Converting a recurring decimal to
a fraction
1. let x equal the recurring decimal
2. multiply both sides of this equation by 10 if 1 digit recurs, 100 if 2
digits recur and so on.
3 .Subtract the original equation from the new equation
4. Rearrange x as a fraction
E.g. x= 0.234234234...
1000x= 234.234234
1000x-x= 234.234234...-0.234234..
999x= 234

### Slide 4

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Upper and lower bounds
Upper bound of a number= the highest value that rounds down to that number
Lower bound of a number= the lowest value which rounds up to that number
Calculating the bounds of s=x+y
Upper bound of s ­ upper bound of x+ upper bound of y
Lower bound of s- lower bound of x+ lower bound of y.
calculating the bounds of d=x-y
Upper bound of d= upper bound of x- lower bound of y
Lower bound of d= lower bound of x- upper bound of y
Calculating the bounds of p=xy
Upper bound of p=upper bound of x multiplied by the upper bound of y
Lower bound of p=lower bound of x multiplied by the lower bound of y
Calculating the bounds of q=x/y
Upper bound of q= upper bound of x divided by the lower bound of y
Lower bound of q= lower bound of x divided by the upper bound of y…read more

### Slide 5

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Percentages
Compound interest= interest paid on the total amount including previous interest
Amount after n years= original amount x multiplier
Increasing an amount by a percentage= work out the original amount and add it to the
original number.
Decreasing an amount by a percentage- work out the percentage of the amount and
subtract it from the original number
Writing one quantity as a percentage of another quantity- write the first quantity as a
fraction of the 2nd quantity and then covert the fraction as a percentage
Finding the percentage profit or loss= use the formula
Percentage Profit/loss = profit/loss/original amount x 100%…read more

### Slide 6

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Contents
Solving Linear equations
Apply operations to both sides of the equation
until the unknown is on its own on one side of
the equation only.
You must- collect like terms and follow the rules
of bidmas and eliminate fractions by multiplying
each term by the lcm of the denominators.
Solutions can be whole numbers, fractions,