HP 42S manual Statistics, Enter 6 Σ+, Sub-menu Cfit

9 Statistics

To enter statistical data we use the function Σ+. For one variable statistic just enter the number and press Σ+. For two variables statistic first enter y, press ENTER and then enter x (without pressing ENTER!) and finally press Σ+.

To clear statistic data just do ▀ CLEAR CLΣ.

The statistical functions are available in ▀ STAT menu and they are:

Σ+: The same of pressing Σ+.

SUM: Calculates the sum of the statistical data.

MEAN: Calculates the mean of the statistical data.

WMN: Calculates the weighted mean (x weighted by y).

SDEV: Sample standard deviation. (To calculate the Population standard deviation you must calculate the mean, add it to statistical data and then press SDEV)

CFIT: This is a sub-menu to fit the data in linear regression, logarithm regression, exponential regression or power regression.

There is also a second line with ALL, LINΣ, ΣREG and ΣRG? Functions.

Example: A particle of mass m1=1kg is at the position x1=2m while a particle of mass m2=3kg is at position x2=6m. What is the position of the center of the mass?

Solution: The position of the center of the mass is given by

x = x1 m1x2 m2

cm m1m2

This is a weighted mean where the physical mass is the statistical weight.

To calculate it using HP-42S we do:

▀CLEAR CLΣ (cleaning statistical data)

1 (This is m1)

ENTER

2(This is x1)

Σ+

3

ENTER 6 Σ+

▀STAT WMN Which gives to us 5.

9.1 The sub-menu CFIT.

The CFIT menu has the following functions:

FCSTX, FCSTY, SLOPE, YINT, CORR, MODL.