General Revision Flashcards
Compound interest means …
The interest accumulated over a number of years, and added to the initial value
What would you type in the calculator to work this out?:
Compound interest: Invest £2000 for 3 years at a rate of 12.5%
2000 x 1.125^3
What is depreciation?
Depreciation is when the value of something decreases
What would you type in the calculator to irk this out?
A car costs £5000 and depreciates by 7.3% for 4 years
5000 x 0.927^4
What would you type in the calculator to work out this?
A coat costs £45 after a reduction of 7%. What was the original price?
45 / 0.93 = £48.39
What would you type in the calculator to work this out?
A slug weighs 8 grams after an increase of 42%. What was its original weight?
8 / 1.42 = 5.6 grams
How do you work out reverse percentages?
1) Get the percentage of the original number. If the percentage is an increase then add it to 100, if it is a decrease then subtract it from 100.
2) Multiply the final number by 100.
3) Divide this number by the percentage
In other words - divide the amount by the multiplier
What is standard form?
Standard form is when a number is expressed in this formula:
a x 10^n
What do you need to remember about upper and lower bounds?
- 99999…. is the same as 1
0. 49999…. is the same as 0.5
If you know tan(x) = 3.54, how would you work out x?
Tan^-1 (3.54)
What is the quadratic formula?
x = -b +/- root (b^2 - 4ac / 2a)
What does the +/- symbol mean in the quadratic formula?
It means you can do two calculations - one with +, the other with -
How can you check your answers to the quadratic formula are correct?
You can substitute your x value into the equation:
ax^2 + bx + c = 0
When you label a trapezium, what are a, b and h?
h = perpendicular height
a and b = length of the parallel lines
