section 2.3

Question 1

particular values ( observations )

Answer 1

of a variable x can be denoted by subscripts x1, x2,etc

Question 2

when do we use the greek capital letter sigma Σ ?

Answer 2

with a a variable next to it show which one is being summed

Question 3

Σ x

Answer 3

stands for the sum of the values of the variable x `

Question 4

the round off rule

Answer 4

round all calculations to one more decimal place than is present in the data . round only , the final answer , not the steps along the way

Question 5

measures of center ( or measures of central tendency )

Answer 5

are descriptive measures that indicate where the center or most typical value of a data set lies

Question 6

mean

Answer 6

is sum of all values of the observations divided by the number of observations . the means is also called the average

Question 7

the sample mean x̄

Answer 7

is represented by the symbol , which is called ‘x-bar’ =Σx/N , where N is the number of values in the population

Question 8

median

Answer 8

is the value that divides the booth 50% of the data from the top 50% . Its the middle value when the values are placed in size order

Question 9

mode

Answer 9

is the value that has the most number of observations (frequency ) but must occur more than once .

Question 10

mean of frequency table formula

Answer 10

the formula Σ x^f/f where x^f is the product of f each class midpoint x^ , times the class frequency f

Question 11

weight mean

Answer 11

another special case of finding average is when we know the values but they are not all equally weighted
x̄ =Σxw/ Σw

Question 12

xw

Answer 12

is the product of each data value x multiplied y its weighted w