Probability Basics - Free Educational videos for Students in K-12

Probability Basics - By tecmath

Transcript


00:0-1	Hey , Welcome to Tech Math channel . What we're
00:01	going to be having a look at in this video
00:02	is just basic probability . It's a nice introduction to
00:06	probability and it's going to be a series of probability
00:09	of videos coming out . So even new probability ,
00:11	this is probably a really , really good start for
00:13	you . So first off in , that's when we
00:16	are talking probability and chance . What we are talking
00:19	about is how likely something is to happen . And
00:24	I'm just going to go Lord straight into some examples
00:26	with these because I think it's the best way to
00:27	explain it . So the example I'm going to have
00:29	a look at is say I threw a coin in
00:32	the air when we throw a coin in the air
00:34	, we have two possibilities of what might happen .
00:37	Okay . The first is it might land on heads
00:41	. Okay . And there's heads or it could land
00:44	on tails . I haven't talked to attempt to draw
00:47	anything for that . Okay . So the way that
00:50	we write this is as follows , when we talk
00:52	about assigning how likely something is to happen , we
00:56	write it like this , the probability say for heads
01:00	happening and we write this as pr for probability of
01:03	heads is equal to and you probably agree there's a
01:06	half chance of that occurring . Okay . And the
01:09	probability of tales happening , There's also a half chance
01:13	of that occurring . There's a 5050 chance , there's
01:15	a one out of two chance of heads occurring .
01:18	There's a one out of two chance of tales occurring
01:20	up to possible outcomes . One of the end of
01:23	the two outcomes , one of them is heads and
01:26	one of them is tails . So I'll go through
01:29	a couple more of these . Okay , In the
01:31	next example , what we're going to have a look
01:33	at is a dice here . Okay , So we
01:35	roll the dice to six sided dice . Now ,
01:38	first off , when we roll a dice it's important
01:42	to think how many possible outcomes are there you might
01:44	say okay there's six possible outcome , there's six outcomes
01:47	. What are those outcomes or we could get a
01:50	one we could get it to we could get a
01:52	three , we could get a four , we could
01:54	get a five , we could get a six ,
01:55	it will land on one of those particular sides up
01:59	. Okay so I can just ask a couple of
02:01	probability questions with these and we'll see how you go
02:04	with them . What's the probability of say Raleigh a
02:07	four ? So out of the six possible outcomes there
02:12	is only 14 there is possibility of one 14 .
02:16	There's one of these out of an entire six possible
02:19	outcomes , there's a one out of six chance .
02:22	What's the probability of rolling an even number ? Okay
02:28	. Yeah you might look and say okay well how
02:30	many possible even numbers others ? One , 2 ,
02:34	324 and six . There are even numbers three of
02:37	those Out of a possible six total outcomes . Okay
02:42	. What about this ? Once the probability of rolling
02:44	a seven ? Mhm . We'll have any sevens are
02:48	here . There's no sevens . There's no chance .
02:51	Out of the six possible outcomes . Okay so you're
02:55	probably getting an idea of how we can assign basic
02:58	probability here and there's a basic rule for it .
03:01	Which is this ? Okay . The probability of an
03:04	event occurring is equal to the number of different ways
03:08	it can occur . Someone said the number of favorable
03:11	outcomes that occur over the total number of outcomes .
03:15	So an example of that might be when we're looking
03:17	at how many ways a dice could be rolled evenly
03:21	. You know the number would come it would be
03:22	even there's three different ways we can get that .
03:25	So it would be three Over a possible total number
03:29	of outcomes of six . Okay . So the probability
03:32	of an event occurring as a rolling a uh an
03:35	even number would be three out of six . And
03:37	so this is a really really handy and important thing
03:40	to think of with probability . Another thing that's important
03:43	to think of , the probability is probably I guess
03:45	the entire range of probabilities that we can have and
03:49	this goes across from say something being totally impossible ,
03:53	okay . Something which is impossible . Um And it
03:56	has a 0% chance of occurring . Okay . Whether
04:01	it is with a dice that might say , I
04:03	said what's the chance that you're throwing a seven ?
04:05	You'd say ? Okay there's zero out of six chance
04:07	that occurring . We would say with this that there
04:10	is a probability of zero . It ranges right through
04:15	to over here . Where we could have absolute certainty
04:19	. Okay I guess I'll just write that down as
04:22	certainty . Okay there's 100% chance of it occurring .
04:27	Uh You know with a dice that we roll any
04:31	number between one and six . There's a six out
04:33	of six chance of that occurring . And we would
04:35	say with this that the probability is equal to one
04:39	because six divided by six is equal to one and
04:41	100% decimal is is equal to one . Now .
04:44	In between that I guess you could actually then say
04:46	well Halfway in between that I guess here we have
04:50	that 50% chance of something occurring . Okay it's a
04:54	equal chance of it occurring I guess equal um You
04:59	know the probability you can think of being three out
05:00	of six a rolling a even or a number or
05:04	then even rolling in um an odd number . The
05:06	probability here would actually be 0.5 . Now you're going
05:12	to see here as we go between here and you
05:15	go from equal chance this way things become increasingly unlikely
05:19	and as we go this way things become increasingly likely
05:23	to occur . It's important thing to get because a
05:25	bit later on it saves you a bit of work
05:28	in terms of you know there's certain things where if
05:31	you know that the probability of something occurring , all
05:33	the total probabilities are one . It's really really handy
05:36	for working things out a bit later on . So
05:38	just just trust me on that . So I'm going
05:40	to get you to do a few examples with this
05:43	. Okay for the first example I'm going to pretend
05:46	we have some marbles we have for red marbles ,
05:50	we have two Blue Marbles and we have three yellow
05:59	marbles . And if we were to pick one of
06:01	these marbles out at random . Okay , so we
06:04	just pick one of these marbles at random . What
06:06	would be the probability of getting a red ? I'll
06:10	get you to answer that . What about the probability
06:13	of getting a blue ? What about the probability of
06:18	getting agreed ? What about the probability of getting any
06:26	color like any color at all ? Uh And I
06:30	don't mean like obviously pink or whatever . I mean
06:32	the probability of getting a red , yellow or blue
06:36	. So I'll get you to work these out .
06:39	Okay , probably be getting it red . There is
06:42	1234 favorable outcomes out of a possible 123456789 outcomes .
06:50	The probability getting a blue , there is two possible
06:53	outcomes out of a possible nine . As you go
06:56	so far . The probability getting a green . What
06:58	did you get for this ? Hey there's zero greens
07:01	out of a possible nine . And the probability of
07:04	getting any color red , a yellow or blue ?
07:07	Well that's a nine out of nine chance . It's
07:09	100% certainty that you are going to get a color
07:11	when you pick one of those marbles . Okay ,
07:14	how'd you go with those ? Okay , through one
07:16	more example . Okay with this example I am going
07:20	to use the word probability itself . So say we
07:23	really get these letters and they would it be one
07:28	of these letters was randomly chosen ? Okay . We
07:30	were to randomly choose this letter . Okay , all
07:33	of this letter or this letter , What would be
07:35	the probability of that letter being chosen being A B
07:39	. What would be the probability of the letter chosen
07:43	being a ? Y . What about the probability of
07:49	getting a veil ? Okay . That is an A
07:53	. And E . And I . And or you
07:57	what about the probability of getting a letter ? Okay
08:01	. When you choose a letter what's the probability of
08:03	you're actually getting a letter ? Um Yeah that will
08:06	do it I think for the minute . So the
08:10	probability of getting A . B . There is two
08:12	out of 123456789 10 11 Possibilities . There is probably
08:22	getting why there is a one possibility out of 11
08:28	. The probably beginning of our there's 1234 favourable possibilities
08:35	out of a total of 11 possibilities . They're probably
08:39	getting a letter at all . Well this you're gonna
08:41	get a letter . I don't know which one is
08:43	going to be but there's an 11 out of 11
08:44	chance . What this one will go one step further
08:46	. What's the probability getting the letter C . You're
08:50	like Okay there's actually no chance of that out of
08:52	11 . So if you can get this straight away
08:55	, you're pretty good . With the basics of probability
08:58	. Now he's going to get harder a bit later
09:00	on , we are going to look at , you
09:02	know , different probabilities and different series that can can
09:05	occur , but they don't worry . If you got
09:07	this bit started , you'll do okay and it'll lead
09:10	you in good stead to get on with the next
09:11	stuff anyway . Hopefully you enjoy this video . Really
09:15	glad to have had you here . Ah look ,
09:16	if you like this video , you know , hit
09:19	that , like hit the like button really , really
09:20	hard . Okay . Uh And thanks for watching anyway
09:24	, See you later . Bye .

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