iStatistics User Guide

The mean adds all of the values (x or y) and divides by the total number of data points n. The weighted mean is the same thing for x except weighted by another number y.

A yacht captain wants to determine how long it takes to change a sail. She randomly closes six members of her crew, observes the minutes required.: 4.5, 4, 2, 3.25, 3.5, 3.75. Calculate the mean and standard deviation.

Inputs Point x = 4.5, 4, 2, 3.25, 3.5, 3.75

Results mean = 3.5 , sample standard deviation = .85

The coach has four new players on the team with heights of 193, 182, 177 and 185 centimeters and weights of 90, 81, 83, and 77 kilograms. Find the mean and population standard deviation of both their heights and weights, the sum the y-data.

Inputs Point x = 193, 182, 177 and 185

Inputs Point y = 90, 81, 83, and 77

Results mean of heights x = 184.25 , mean of weights y = 82.75

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Linear Regression is a statistical method of estimation and forecasting. It is used to find a straight line that best fits a set of x,y data. There must be at least two different x,y pairs. The straight line provides the relationship between the x and y variables: y = mx + b, where m is the slop and b is the y intercept. The correlation coefficient below shows how well the x,y data correlate, if close to 1 or -1 then data pairs lie very close to a straight line, a value of 0 indicates it is not a good fit.

Al's Azaleas advertises on a local radio show. For the past six weeks, the manager has kept records of the number of minutes of advertising that were published, and the sales for the week.

Inputs x = 2,1,3,5,5,4

Inputs y = 1400, 920, 1100, 2265, 2890, 2200

What is the y-intercept, the slop and the correlation coefficient?

Regression Slope (m): 425.88

Regression Intercept (b): 376.25

Correlation Coefficient (r): .90

What is the estimated level of sales if the business purchased 7 minutes.

Answer : 3,357.375

How many minutes of advertising should Al buy for sales of $3000?

Answer : 6.16

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How many different hands of cards can be dealt from a standard deck of 52 cards?

Inputs n = 52, r=5

Results

Combinations 2,598,960.00

Permutations 311,875,200.00

Out of 20 different items, how many groups of 5 can be chosen with no consideration of order?

Inputs n = 20, r=5

Results

Combinations 15,504.00

Out of 20 different items, how many groups of 5 can be chosen in a particular order?

Inputs n = 20, r=5

Results

Permutations 1,860,480.00