Finding Probability | Basic Probability | Math with Mr. J

[Music] Welcome to Math with Mr. J. In this video, I'm going to cover how to find probability. We will go through five basic probability examples using playing cards. Now, remember, probability tells us how likely something is to happen. In other words, the chance of something happening. And we can use the probability formula to find the probability of something. We have P for probability and then in parentheses we have event and an event is whatever we are finding the probability of. Basically an event is one outcome, one result or a group of outcomes, a group of results that we are interested in that we are focused on. The probability of an event equals the number of favorable outcomes over the total number of possible outcomes. The number of favorable outcomes are all of the ways the event can happen. The total number of possible outcomes, that's the total number of things that can happen. The total number of possibilities. Let's jump into our examples here where we are going to say that the playing cards are face down on a table so we cannot see what they are. We're going to randomly select one. So each card has an equal chance of being selected. We have five events here that we are going to find the probability of. Let's start with number one where we have the probability of picking a nine. So picking a nine is our event. If we randomly pick one card, what's the probability we pick a nine? And we're going to write the probability as a fraction, decimal, and percent. Let's start with the number of favorable outcomes. So, how many ways can this event happen? How many cards have a nine? So, looking at the cards, we can see one. One card has a nine. So, our numerator is one. Now we need the total number of possible outcomes. The total number of things that can happen. So how many possibilities do we have here? How many cards are there? Five. So five is our total number of possible outcomes. So five is our denominator. We can pick any one of those five cards. So we have five possible outcomes, five possible results. That's our fraction 1 over 5 1/5. And that's our probability. We have a 1 out of five chance of picking a nine. Now let's write that as a decimal and a percent. 1/5 as a decimal equals 0.2 210th. Remember divide the numerator the top number by the denominator the bottom number. to go from a fraction to a decimal. And then we can get our percent by multiplying the decimal by 100, which a quick way to do that is move the decimal twice to the right. So our percent here is 20%. So this is the probability of picking a nine. This describes our chances. This helps us understand how likely it is to happen. Let's move on to number two where we have what's the probability of picking an odd number. Let's start with the number of favorable outcomes. So how many cards have an odd number? We have a seven, a five, a nine, a seven, and a three. So all five cards. We have five favorable outcomes. So five is our numerator. Then our total number of possible outcomes is five as well. There are five total cards. So our denominator is 5. And that's our fraction 5 over 5. 5 fths. We have a five out of five chance of picking an odd number. Now let's divide the numerator by the denominator to get our decimal. That's going to be one. One whole. Keep in mind whenever we have the same number on the top and bottom our decimal is just one. Now since this is a whole number we typically don't write the decimal point. But remember a decimal point comes after a whole number after the ones place. Then our percent here we multiply that decimal by 100 and that's going to be 100%. Five out of five cards have an odd number. So, we have a 100% chance. This is what we call a certain event. We're 100% certain it will happen. Let's move on to number three. What's the probability of picking a card with hearts? Favorable outcomes. Well, there are three cards with hearts. So, we have three favorable outcomes. That's our numerator. And as far as the total number of possible outcomes, that's five. There are five total cards. So our fraction is 3 over five. 3 fifths. We have a three out of five chance of picking hearts. As far as our decimal here, 3 / 5 gives us 0.6 6/10. Then we can multiply that decimal by 100 to get our percent. Our percent here is 60%. And that's our probability of picking hearts. Moving on to number four, we have what's the probability of picking a queen? Favorable outcomes here. Well, it looks like we don't have any queens at all. So, this is going to be zero. We have zero favorable outcomes. There aren't any ways that this event can happen. And then our total number of possible outcomes is five. There are five cards in total. And that's our fraction 0 over five. Zero fifths. We have a zero out of five chance of picking a queen. Then as far as our decimal, that's going to be zero. And our percent is going to be 0%. We have no chance of picking a queen. This is what we call an impossible event. Lastly, let's move on to number five where we have what's the probability of picking a three or a five. So, think if we randomly pick one card, we want either a three or a five. As far as favorable outcomes, how many cards have a three or a five? We have one three and one five. So that gives us two favorable outcomes over the total number of possible outcomes five. Our fraction 2 over five two fifths. We have a two out of five chance of picking a three or a five. There are two cards that we can pick here that will make our event happen. Either will work. picking the five card or picking the three card. Now for the decimal, two divided by five gives us 0.4 4/10. And then multiplying that decimal by 100 gives us our percent 40%. And that's our probability of picking a three or a five. So there you have it. There's some basic probability examples using playing cards. I hope that helped. Thanks so much for watching. Until next time, peace.