Maths- Y10 Notes as cards Flashcards
Two events are independent if the probability of one event is unaffected by the probability of another.
e.g. What is the probability of flipping two heads in a row? HH TT HT TH 1/4 = 1/2 x 1/2
Multiplication Rule-
P (a and b) = p(a) x p(b)
*a and b are independent events
Additional Rule-
For mutually exclusive events (events that cannot occur at the same time)
P(A or B) = P(A) + P(B)
Ratio-
Ratio is used to describe a fraction
e.g. 9:6 = 3:2
Always simplify to as low as possible!!
HCF-
Write each number as a product of its primes.
To find the HCF, multiply all factors which appear in both lists
60= 2, 2, 3, 5 72= 2, 2, 2, 3, 3
eg. HCF of 60 and 72 is 2 x 2 x 3= 12
LCM-
The LCM is found by multiplying all the factors which appear in either list.
60= 2, 2, 3, 5 72= 2, 2, 2, 3, 3
2 x 2 x 2 x 3 x 3 x 5 = 360
BIDMAS-
Brackets, Indices, Division, Multiplication, Addition, Subtraction
Percentages-
To change a fraction or a decimal to a percentge you multiply by 100%
e.g. 3/8 = (3/8 x 100/1)%= 37.5%
Working out percentages-
eg 7% of £3200
= 7/100 x 3200/1 = £224
or 0.07 x 3200 = £224
Percentage Increase-
£8400 is increased by 5%= 105% of £8400
= 1.05 (percentage multiplier) x £8400
= 8200
Decrease therefore would be (eg) 0.95 x 8400
Compound Interest-
“A bank pays a fixed interest of 10% on money in accounts. Amanda put £500 in the bank, how much money will she have…”
after:
one year= 500+(10% of 500)= £550
2 years= 550 + (10% of 550)= £605
3 years= 605 + (10% of 605)= £665.50
GENERAL FORMULA… n 1.10 x 500 1.10= percentage increase n= years 500= money put in
Reverse Percentages-
Finding the original price
eg cost price = 100% selling price= 100% + 40% £63 = 140% 63/140 = 1% 1%= £0.45 100%= $0.45 x 100 =£45
Fractions-
To add and subtract you must have the same denominator
Multiplying-
Top x top
Bottom x bottom = simplify outcome
When dividing, multiply the reciprocal (upside down) of what you want it to be divided by.
Surds-
a to the power of 0 is always 1
surds are numbers like ⎷3 and ⎷4
It is sometimes helpful to write an expression with an integer denominator- RATIONALISING THE DENOMINATOR
e.g. 6/ route 3
6⎷3 = 6 x ⎷3 = 6 ⎷3 = 2 ⎷3
⎷3 x⎷3 3
A surd is a square root which cannot be reduced to a whole number.
⎷ab = ⎷a x ⎷b
⎷a x ⎷a = a
Standard Form-
n
A x 10
A is always 1-10
eg 15 000 000 = 1.5 x 10^7
Bounds-
12cm long piece of fabric
- 5= lower bound
- 5= upper bound
Averages-
Median- Arrange smallest to largest, this is then the middle number. If there are two middle numbers its the middle of these numbers.
Mean- All data aded and divide by the number of items.
Mode- Number which occurs most frequently
Range- (Largest value) - (smallest value)= range
Moving Averages
To see if there is a trend in the sales figures you can use a moving average
4 point m.a. is most common and involves finding the mean of four quarters
This is then plotted on a graph
Frequency Polygons and scatter graphs-
Vertical axis always= frequency in the frequency polygon the boxes of the bar chart are replaced by a line joining the tops of their mid points
discrete data= counting continuos data =measuring
eg. Weak correlation
Always say if it is weak/strong positive/negative or if there is no correlation
Box and Whisker-
Lowest value
Lower quartile
Median
Upper quartile
Highest value
To find lower, median and upper put numbers in order and the first 1/4, 1/2 and 3/4
interquartile range = upper quartile - lower quartile
Histogram-
The area of each bar shows the frequency of the data.
Bars have varying widths
vertical axis= frequency density
Cumulative frequency=
S shaped curve when on a graph
Data from a frequency table
y = mx + c