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GED Math - Probability
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•What is the formula for basic probability?
•How do we calculate consecutive outcomes like the probability of flipping a coin with the result of heads three straight times?
Basic Probability
Basic probability = number of good outcomes/number of total outcomes. What does this look like? Say you are flipping a coin and you pick heads. There is one good outcome (heads) and two total possible outcomes (heads and tails). Therefore, the probability of getting a good outcome is ½.
Dice Questions
What about rolling a die and you want a four. There are six possible outcomes, but only one that you like. The probability of rolling a four is 1/6.
Consecutive Events
More complicated probability questions ask about consecutive outcomes. This would be something like what are the chances of getting heads three straight times? With questions like this, we multiply the probabilities together. With heads/tails questions, the chance of each is always ½. The likelihood, or probability, of three straight heads is ½ x ½ x ½, which equals 1/8.
What do you think the probability of rolling three straight four’s is? You’ve got a 1/6 chance with every roll, so 1/6 x 1/6 x 1/6 = 1/216.
Card Questions (Consecutive Events)
The most challenging probability question you will see involves consecutive events that do not have the same probability each time. What does this mean? Say you have a deck of cards and the question is what is the likelihood of getting consecutive aces with one full deck of cards, but after you draw a card you don’t leave it in the deck. In a regular deck there are four aces and 52 total cards. When drawing the first card, there is a 4/52 chance that I will draw an ace. 4/52 can be reduced to 1/13 by dividing each side by four. However, if I draw an ace on the first card, there are now only three aces left in the deck and 51 cards total. To get the answer, I will multiply 1/13 by 3/51, which results in 3/663 chance that I draw consecutive aces.
#ged #GedMath
•What is the formula for basic probability?
•How do we calculate consecutive outcomes like the probability of flipping a coin with the result of heads three straight times?
Basic Probability
Basic probability = number of good outcomes/number of total outcomes. What does this look like? Say you are flipping a coin and you pick heads. There is one good outcome (heads) and two total possible outcomes (heads and tails). Therefore, the probability of getting a good outcome is ½.
Dice Questions
What about rolling a die and you want a four. There are six possible outcomes, but only one that you like. The probability of rolling a four is 1/6.
Consecutive Events
More complicated probability questions ask about consecutive outcomes. This would be something like what are the chances of getting heads three straight times? With questions like this, we multiply the probabilities together. With heads/tails questions, the chance of each is always ½. The likelihood, or probability, of three straight heads is ½ x ½ x ½, which equals 1/8.
What do you think the probability of rolling three straight four’s is? You’ve got a 1/6 chance with every roll, so 1/6 x 1/6 x 1/6 = 1/216.
Card Questions (Consecutive Events)
The most challenging probability question you will see involves consecutive events that do not have the same probability each time. What does this mean? Say you have a deck of cards and the question is what is the likelihood of getting consecutive aces with one full deck of cards, but after you draw a card you don’t leave it in the deck. In a regular deck there are four aces and 52 total cards. When drawing the first card, there is a 4/52 chance that I will draw an ace. 4/52 can be reduced to 1/13 by dividing each side by four. However, if I draw an ace on the first card, there are now only three aces left in the deck and 51 cards total. To get the answer, I will multiply 1/13 by 3/51, which results in 3/663 chance that I draw consecutive aces.
#ged #GedMath
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