summarising data

Question 1

what is the mean?

Answer 1

average of all the values so add them all together and divide by the amount of numbers

Question 2

what is the mean?

Answer 2

average of all the values so add them all together and divide by the amount of numbers

Question 3

what is the median?

Answer 3

the middle value (n+1)/2
if it’s even it’s the average of the two middle values

Question 4

what is the mode?

Answer 4

the most common value or most common group

Question 5

how do you find the median of grouped data?

Answer 5

L+W(n/2-cf over f)

L is the lower bound

W is the width of the median category

n is the sum of all frequencies

cf is cumulative frequency of the preceding class aka the class before

f is the frequency of the median category

Question 6

how do you find n for median grouped data?

Answer 6

add all the frequencies together

Question 7

how do u find L for median grouped data?

Answer 7

you find the lower bound of your median category to do this you find the number between the lowest on the median and the upper on the class before and find the middle

Question 8

how do you find w in median grouped data?

Answer 8

you find the upper bound of your data and then the lower bound and take them away from each other

Question 9

how do you find cf?

Answer 9

add the frequencies together and plot them as you add them

Question 10

how do you find the mean of grouped data?

Answer 10

find the mid points

times all the midpoints by the

frequency’s/ units

then finally divide by total frequency or units

Question 11

How do you find the range?

Answer 11

maximum-minimum

Question 12

what is the calculation for standard deviation of grouped data?

Answer 12

square root of f(midpoint-mean) squared/ n-1

Question 13

how do you do standard deviation for grouped data?

Answer 13

1. find the midpoint of the class range (ADD TOGETHER AND/ 2)
   2.times the frequency column by midpoint
2. frequency x midpoint added together and tat is the mean frequency
3. plot this mean in a different column
4. each class range midpoint take away the mean
   6 square all these values and times by the frequency
   7 add up
   8 divide all by frequency-1

Question 14

what is the calculation for standard deviation for population?

Answer 14

square root of x-mean squared/ n

Question 15

how to find standard deviation for population

Answer 15

1 find the mean of data
2 take away each number by mean and square it and add all together
3 divide that by number of numbers
4 square root it

Question 16

how do you find the variance?

Answer 16

square of standard deviation

Question 17

how to do box and whisker plots

Answer 17

1 arrange values in ascending order
2 break data into equal parts
3 median of the lower half and upper half
4 find the minimum and max value
5 find the interquartile range value which is the difference between q1 and q3
6 find any outliers by doing q1-1.5 x iqr q3+1.5 x iqr
7 if the min and max are within those two numbers there is no outliers
8 create box and whisker

Question 18

how do you work out IQR?

Answer 18

the difference between q1 and q3

Question 19

how do you work out the quartiles?

Answer 19

Q1 = (N+1)/4

Q3 = 3x(N+1)/4
which gives you the value eg if you get 12.75 it will be 3/4 of the way between your 12th and 13thvalue

N is the number of observations eg how many numbers

Question 20

how do you work out your inner fences?

Answer 20

Q1-1.5 x IQR, Q3 + 1.5 X IQR

Question 21

what does the inner fence show?

Answer 21

possible outliers “o”

Question 22

how do you find the outer fence?

Answer 22

Q1 - 3 X IQR, Q3 + 3 X IQR

Question 23

what does the outer fence show?

Answer 23

probable outliers “*”