Statistics

Question 1

Median

Answer 1

ascending

Question 2

Median is not affected by the

Answer 2

Extremes or the endpoints or outliers but the mean is

Question 3

mean, median, mode

Answer 3

1 mean, 1 median, 1/more.no mode

Question 4

When are mean and median the same?

Answer 4

a) If a list is evenly spaced;

b) whenever the list is symmetrical around its center

Question 5

Outlier

Answer 5

Pulls the mean in its direction; if big number, mean>median

Question 6

Weighted averages

Answer 6

1)using sums
2)Proportions
p1+p2+p3=1
p1a1+p2a2+p3a3= weighted average
3) proportions only involving two groups
if p1+p2=1; 1>p2 then average is going to be closer to A1; d1 dist a a1 from a and d2 is dist of a2 from a, since a1 is closer to a, d1 is going to be less than d2; then p1/p2=d2/d1; to find the dist: a1-a2/(p1+p2) and then use the which one is closer logic

Question 7

p1

Answer 7

5:6= 5/(5+6)

Question 8

SD

Answer 8

Take a list, sub mean from every item on the list, average of sd’s is 0;

Question 9

If all the numbers are identical sd=

Answer 9

0

Question 10

If all the numbers on the list are exactly same dist from the mean

Answer 10

Sd is that dist

2,2,2,8,8,8; mean=5

Question 11

Set with most number clustered towards the extremes higher sd

Answer 11

higher sd

Question 12

If we add/sub same number to every number on the list

Answer 12

sd does not change

Question 13

SD only has to do with spacing

Answer 13

Not with where they are on the number line: left right reflection

Question 14

If we multiply every number by k then sd

Answer 14

sd*k

Question 15

If we include big outliers

Answer 15

mean wil go up and sd will go up

Question 16

If we add numbers that won’t change the mean

Answer 16

add 1 below and 1 above; mean+k and mean-k; won’t change the mean, and added numbers further than the mean for the std deviation will increase the mean:

mean is 50, sd 5
40,60 since 10>5; increase
45 and 55; since 5=5 sd=5
47 and 53, 3

Question 17

What pair of numbers would we add to the set that would decrease SD the most

Answer 17

the numbers that are equal to the mean because the distance is 0

Question 18

How to calc sd

Answer 18

start with list; calc mean; sub mean from every number; square that list, find avg; and sq root of that;

Question 19

List of any 9 consecutive integers

Answer 19

2.92

Question 20

sd is only about the dist

Answer 20

Doesnt matter where it is on the number line!!!!

Question 21

Bell curve

Answer 21

34%; +/- 13.5%; mean=median;