# 7.1 Probability: part 2

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## Relative frequency vs. Probability

There are two approaches to determining the probability associated with any particular event of a random experiment:

1. determining the total number of possible outcomes and calculating the probability of each outcome using the definition of probability
2. performing the experiment and calculating the relative frequency of each outcome

Relative frequency is defined as the number of times an event happens in a statistical experiment divided by the number of trials conducted.

It takes a very large number of trials before the relative frequency of obtaining a head on a toss of a coin approaches theprobability of obtaining a head on a toss of a coin (in fact, if the probability of an event occurring is something other than 1, i.e. it is always true, or 0, i.e. it is never true, then probability is only absolutely accurate when an infinite number of trials is conducted). For example, the data in [link] represent the outcomes of repeating 100 trials of a statistical experiment 100 times, i.e. tossing a coin 100 times.

 H T T H H T H H H H H H H H T H H T T T T T H T T H T H T H H H T T H T T H T T T H H H T T H T T H H T T T T H T T H H T T H T T H T T H T H T T H T T T T H T T H T T H H H T H T T T T H H T T T H T

The following two worked examples show that the relative frequency of an event is not necessarily equal to the probability ofthe same event. Relative frequency should therefore be seen as an approximation to probability.

Determine the relative frequencies associated with each outcome of the statistical experiment detailed in [link] .

1. There are two unique outcomes: H and T.

2.  Outcome Frequency H 44 T 56
3. The statistical experiment of tossing the coin was performed 100 times. Therefore, there were 100 trials, in total.

4. $\begin{array}{ccc}\hfill \mathrm{Probability of H}& =& \frac{\mathrm{frequency of outcome}}{\mathrm{number of trials}}\hfill \\ & =& \frac{44}{100}\hfill \\ & =& 0,44\hfill \\ \\ \hfill \mathrm{Relative Frequency of T}& =& \frac{\mathrm{frequency of outcome}}{\mathrm{number of trials}}\hfill \\ & =& \frac{56}{100}\hfill \\ & =& 0,56\hfill \end{array}$

The relative frequency of the coin landing heads-up is 0,44 and the relative frequency of the coin landing tails-up is 0,56.

Determine the probability associated with an evenly weighted coin landing on either of its faces.

1. There are two unique outcomes: H and T.

2. There are two possible outcomes.

3. $\begin{array}{ccc}\hfill \mathrm{Relative Frequency of H}& =& \frac{\mathrm{number of favourable outcomes}}{\mathrm{total number of outcomes}}\hfill \\ & =& \frac{1}{2}\hfill \\ & =& 0,5\hfill \\ \\ \hfill \mathrm{Relative Frequency of T}& =& \frac{\mathrm{number of favourable outcomes}}{\mathrm{total number of outcomes}}\hfill \\ & =& \frac{1}{2}\hfill \\ & =& 0,5\hfill \end{array}$

The probability of an evenly weighted coin landing on either face is $0,5$ .

## Project idea

Perform an experiment to show that as the number of trials increases, the relative frequency approaches the probability of a cointoss. Perform 10, 20, 50, 100, 200 trials of tossing a coin.

## Interpretation of probability values - (not in caps, included for completeness)

The probability of an event is generally represented as a real number between 0 and 1, inclusive. An impossible event has aprobability of exactly 0, and a certain event has a probability of 1, but the converses are not always true: probability 0 events are not always impossible,nor probability 1 events certain. There is a rather subtle distinction between "certain" and "probability 1".

#### Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
how did you get the value of 2000N.What calculations are needed to arrive at it
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