14 - Statistics

Question 1

How to find median: EVEN number of elements

Answer 1

Divide by two, then take average of that position + position after

(E.g. 1234 - median is avg of 2 and 3 = 2.5)

Question 2

How to find median: ODD number of elements

Answer 2

Add 1 to number of items, divide by 2: n+1/2

(E.g. 1, 3, 5, 6, 10: 6/2 = 3)

Question 3

How to find positive correlation when looking at two variables

Answer 3

As one variable goes up, other goes up
Higher values go together and lower values go together (e.g profitability 1& customer retention 2 AND profitability 5 & cust ret 6)

Question 4

What holds true in an evenly spaced set

Answer 4

Mean = Median

Question 5

If we are given the mean, how can we calculate the sum

Answer 5

sum = mean x number of terms (from avg formula)

Question 6

Knowing that the Mean = Median is one way of finding the average of an evenly spaced set.

What is the second way? Find mean of integers from 101 to 202 inclusive

Answer 6

Add first and last term and divide by 2
101+202/2=303/2=151.5

Question 7

How many integers are there from 101 to 202, inclusive

Answer 7

(202 - 101) + 1 = 102

Question 8

How to find total number of multiples of 2 OR 3 in a range

Answer 8

Multiples of 2 + multiples of 3 - multiples of LCM (6)

Question 9

total number multiples of 2 OR 3 but not both

Answer 9

Multiples of 2 + multiples of 3 - 2 x multiples of LCM (6)

Question 10

Counting number of multiples in a range (general + example)

E.g. how many multiples of 3 between 17 and 41, inclusive

Answer 10