Probability - Calculating Probability
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00:00hi kids as we learned a few basics about probability in previous lesson now we
00:09are ready to learn how we can find the probability in numbers so let's get
00:15started we can find probability of an outcome or case in a probability
00:23experiment with the formula number of favorable cases divided by total number
00:33of equally likely cases let's learn it more with help of a few easy examples
00:41example if a coin is tossed what is probability of occurrence of the head
00:49our formula is number of favorable cases divided by total number of equal likely
00:59cases here the total number of equally likely cases are two that is heads or
01:07tails and the favorable case that is the case for which we want to find the
01:14probability is one that is coming up of the head so probability of occurrence of
01:23the head is 1 by 2 here 1 is the favorable case and 2 is the total number
01:33of cases possible now let's take another example if a coin is tossed what is
01:42probability of the coming up of the tail we know the formula is number of
01:50favorable cases divided by total number of equally likely cases here the total
01:57number of equally likely cases are two that is heads or tails and the favorable
02:04case that is the case we want the case for which we are finding the probability
02:10is one that is coming up of the tail so probability of occurrence of the tail is
02:18equals 1 by 2 we also learn here that coming up of the head and tail have the
02:27same probabilities both have probabilities 1 by 2 now let's take
02:35another example example now if I toss a dice what is the probability of getting
02:44to we know probability is number of favorable cases divided by total number
02:52of equally likely cases and the number of favorable cases here is one that is
02:59getting two on the dice and the total number of cases are six we know six cases
03:08are there at most possible in a dice that is numbers 1 to 6 so probability is
03:171 by 6 let's take another example now if I toss a dice what is the probability of
03:28getting an odd number we know probability is number of favorable cases
03:36divided by total number of equally likely cases number of favorable cases
03:43here are three that is getting an odd number one three or five in a dice and
03:52total number of cases possible are six as we know there are six numbers in a
04:00dice numbering from 1 to 6 so probability of getting an odd number is
04:073 by 6 or 1 by 2 now let's take another example now what is the probability of
04:18getting the numbers 2 or 5 on the dice we know the probability is number of
04:26favorable cases divided by total number of equally likely cases or the total
04:34number of cases possible number of favorable cases possible here are two
04:42that is getting numbers 2 or 5 total number of cases are 6 we know there are
04:526 numbers on the dice numbered from 1 to 6 so the probability of getting numbers
05:002 or 5 is 2 by 6 or 1 by 3 so we have learned how to find probabilities of
05:11various outcomes when we toss a single die or coin now let's learn how to find
05:18probabilities of something else we have a bag of balls where we have five red
05:28balls and two blue balls we take out a ball without looking into the bag so
05:37let's find out the probabilities in different cases let's find probability
05:45of getting a red ball we know the formula is probability of getting red
05:54ball is number of favorable cases divided by total number of equally
06:01likely cases and the number of favorable cases are five as five red
06:08balls are there and total number of equally likely cases are seven as seven
06:17balls are there so probability of getting a red ball is 5 by 7 let's take
06:27another example let's find the probability of getting a blue ball we
06:34know the probability of number of favorable cases divided by total number
06:41of equally likely cases and here the number of favorable cases are 2 as
06:48number of blue balls are 2 and total number of equally likely cases are 7 as
06:587 balls are there so probability for getting a blue ball is 2 by 7 so kids
07:10are you getting how we find our probability of our favorable cases now
07:17let's take one more example we have a bag of balls where we have two black
07:26balls four red balls and six blue balls we take out a ball without looking into
07:35the bag so let's find out probabilities in different cases so let's find out
07:44probabilities in different cases let's find probability of getting a black ball
07:50where we have two black balls four red balls and six blue balls we know the
07:59formula is number of favorable cases divided by total number of equally
08:06likely cases number of favorable cases equals 2 as 2 black balls are there and
08:17the total number of equally likely cases or the possibility of outcomes are 12 as
08:26balls are there so probability for getting a black ball is 2 by 12 or 1 by
08:366 now let's find probability of getting a red ball we know the formula is number
08:45of favorable cases divided by total number of equally likely cases or the
08:52total number of possible outcomes number of favorable cases that is the
08:58cases we want are four as four red balls are there and total number of equally
09:06likely cases that is total number of possible cases are 12 as 12 balls are
09:14there so probability for getting red ball equals 4 by 12 or 1 by 3 now let's
09:25take another example let's find probability of getting a white ball we
09:34know the formula is number of favorable cases divided by total number of equally
09:42cases or the possible number of cases number of favorable cases are zero as no
09:54white ball is there total number of equally likely cases or the possible
10:01number of cases is 12 as 12 balls are there so probability for getting the
10:10white ball is 0 by 12 or 0 so when you get 0 probability it means the event has
10:21no probability to occur now let's find probability of getting a
10:29ball that is just any ball we know the formula is the number of favorable cases
10:37divided by total number of equally likely cases or the possible number of
10:43cases number of favorable cases is 12 as 12 balls are there as we are finding the
10:51probability of getting any ball total number of equally likely cases or the
10:58possible number of cases is also 12 as 12 balls are there so probability of
11:06getting any ball is 12 by 12 or 1 and probability of 1 means the event is
11:15certain to occur so kids probability is a number which ranges from 0 to 1 0
11:24means no probability and 1 means event is certain to occur and probability
11:32between 0 and 1 means it has some probability to occur but not certain to
11:39occur so kids you now know you have a fair idea about what is probability what
11:47are equally likely cases or possible outcomes what are favorable cases and
11:54how to find probability now you may go ahead and take a quiz to learn more
12:00bye bye