Sharp EL733A EL-733A Operation Manual - Page 76

6.95

[DATA

4.03

6.57

(DATA

5.85

(DATA

7.42

IDATA

6.11

'DATA

4.67

(DATA

lad

[DATA)

Result:

6.08

Your

fl

eet

of

trucks

averaged

6.08

miles

per

gallon

during

this

last

month.

THE

TIE

CFAI

KEY

AND

THE

2n

ECCT0

FUNCTION

Pressing

the

(DATA)

key

in

STAT

mode

after

entering

a

single

datum

accumulates

that

datum

for

the

statistical

functions.

When

you

press

this

key,

you

will

notice

that

the

calculator

keeps

track

of

how

many

data

you

have

keyed

in

by

counting

them

in

the

display.

This

displayed

number

is

called

"n."

Pressing

FM

M

brings

"n"

to

the

display.

In

one

-variable

statistics,

the

data

are

referred

to

in

the

function

names

as

"x."

Thus,

for

one

-variable

statistics,

the

functions

that

you

can

use

are

El

(

x

-bar

or

mean),

(sample

standard

deviation),

[ox)

(population

standard

deviation),

M

(the,

sum

of

the

x's),

and

P1

(the

sum

of

the

x's

after

they

have

been

squared).

STANDARD

DEVIATION

To

calculate

the

standard

deviation

for

the

above

list

of

mileages,

you

fi

rst

have

to

determine

which

type

of

standard

deviation

applies.

The

[2ndFI

El

key

calculates

the

"sample

standard

deviation"

and

the

12

nd

key

calculates

the

"population

standard

deviation."

The

"sample

standard

deviation"

.assumes

that

the

data

you

have

keyed

in

are

a

sample

of

a

large

population

for

which

you

are

trying

to

estimate

the

standard

deviation.

The

"population

standard

deviation"

assumes

that

the

data

you

have

keyed

in

are

the

entire

population.

In

the

case

of

the

truck

mileages,

the

"population

standard

deviation"

is

the

one

you

would

want

to

calculate,

because

you

own

only

12

trucks

and

those

12

trucks

are

all

you

are

interested

in

(they

are

the

entire

population).

If

your

calculations

were,

for

example,

for

the

benefit

of

the

EPA

to

estimate

the

mileage

for

a

certain

model

truck

based

on

a

sample

of

12

road

tests,

the

"sample

standard

deviation"

would

be

your

deviation

of

choice,

because

the

EPA

would

take

your

results

and

apply

them

to

all

trucks

of

that

model.

For

the

list

of

numbers

that

you

have

keyed

in,

press

(2ndF)

M

to

calculate

the

population

standard

deviation

(1.05)

and

press

12ndFJ

El

to

calculate

the

sample

standard

deviation

(1.09).

The

variance

is

the

standard

deviation

squared.

Press

FR

n

to

calculate

variance

after

calculating

the

standard

deviation.

THElai

AND

FUNCTIONS

As

mentioned

before,

the

M

function

returns

the

total

of

the

list

of

numbers

that

you

enter

using

the

[DATA)

key,

and

the

function

returns

the

result

that

you

would

get

if

you

squared

all

those

numbers

and

then

added

them

together.

In

the

average

mileage

example

that

we

have

used

in

this

section,

the

total

and

the

sum

of

the

squares

would

probably

not

be

something

you

were

interested

in

knowing

(unless

you

were

going

to

use

those

values

in

some

other

statistical

formulas).

However,

if

you

were

interested

in

those

values,

you

would

fi

nd

that

pressing

12SF)

ri

would

give

you

a

result

of

72.99

and

that

pressing

ISM

ri

would

give

you

a

result

of

457.11.

[Er)

149

149

Sharp EL733A EL-733A Operation Manual - Page 76

Sharp EL733A Manual

Page 76 highlights