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Probability
The probability of a certain event is a number expressing the likelihood that a specific event will occur, expressed as the ratio of the number of actual occurrences to the number of possible occurrences. In mathematics, it is a measure of how often an event will happen and is the basis of statistics.
14,643 Questions
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What is the probabality of flipping three heads when flipping three coins one after another?
The probability of flipping three heads when flipping three coins is 1 in 8, or 0.125.
It does not matter if the coins are flipped sequentially or simultaneously, because they are independent events.
What is the probability of choosing an ace from a standard deck of playing cards?
4 in 52, or 1 in 13, or about 0.0769.
What is the expected value of rolling two dice?
The most probable result of rolling two dice is a sum of seven. The probability of rolling a seven is 1 in 6 or about 0.167.
All of the other possible sums have decreasing probability, all the way down to 1 in 36 or about 0.0278 for a sum of two or a sum of 12.
How can you find the probability of two mutually exclusive events?
The calculation is equal to the sum of their probabilities less the probability of both events occuring.
If two events are mutually exclusive then the combined probability that one or the other will occur is simply the sum of their respective probabilities, because the chance of both occurring is by definition zero.
The probability is 5/9.
What is the probability of picking odd numbers from 1 to 20?
Since there are 10 odd numbers (1, 3, 5, 7, 9, 11, 13, 15, 17, 19) in the 20 numbers (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20), the probability of picking an odd number in a random sample is 10 in 20, or 1 in 2, or 0.5.
z = (x-mean)/sd = (16.1-15.2)/0.9 = 0.9/0.9 = 1
Pr(Z > 1) = 15.8655 %
The first set would have most data points very close to 50 while in the second set they would be much further away.
What is the probability of getting a sum of 14 if four dices thrown together?
The probability is 146/1296 = 0.1127
What is the probability of getting sum 7 if you throw two dice?
With two dice the following totals are possible
....... Dice A .. Dice B
- 2 - 1 ..... 1
- 3 - 1 ..... 2
- 3 - 2 ..... 1
- 4 - 1 ..... 3
- 4 - 2 ..... 2
- 4 - 3 ..... 1
- 5 - 1 ..... 4
- 5 - 2 ..... 3
- 5 - 3 ..... 2
- 5 - 4 ..... 1
- 6 - 1 ..... 5
- 6 - 2 ..... 4
- 6 - 3 ..... 3
- 6 - 4 ..... 2
- 6 - 5 ..... 1
- 7 - 1 ......6
- 7 - 2 ..... 5
- 7 - 3 ..... 4
- 7 - 4 ..... 3
- 7 - 5 ..... 2
- 7 - 6 ..... 1
- 8 - 2 ......6
- 8 - 3 ..... 5
- 8 - 4 ..... 4
- 8 - 5 ..... 3
- 8 - 6 ..... 2
- 9 - 3 ..... 6
- 9 - 4 ..... 5
- 9 - 5 ..... 4
- 9 - 6 ..... 3
- 10 - 4 ..... 6
- 10 - 5 ..... 5
- 10 - 6 ..... 4
- 11 - 5 ..... 6
- 11 - 6 ..... 5
- 12 - 6 ..... 6
So, there are 36 different combinations of how the dice might land and 6 of those total 7. Therefore it is 6 chances in 36 that you'll get 7, which reduced to 1 in 6.
What to do when the z score is not in the z score chart?
The average z score chart lists z scores with three significant figures.
For example, you can find the z score -1.81 on the chart, but not -1.812 or -1.818.
In the case that you wish to look up a z score with more than three significant figures, round it to three significant figures and then use the chart.
OR
You can also use a calculator if you wish to get more accurate results. The link for calculator is mentioned below.
Is mean directly proportional to standard deviation?
No. Not at all. Whoever told you that fails statistics forever.
Is variance directly proportional to standard deviation?
Variance isn't directly proportional to standard deviation.
What is the probability of rolling a 1 on 2 dice?
Assuming normal dice, the answer is 0, since it is impossible to roll a 1 on 2 dice = the least you can get is 1 + 1 = 2.
What does a high z score mean?
It means that the random variable in question is considerably greater than the mean.
It is the sampling distribution of that variable.
How many different ways can you arrange 15 different items?
The number of different ways that you can arrange 15 different items is given by the permutations of 15 things taken 15 at a time. That is 15 factorial, or 1,307,674,368,000.
How many different ways can you arrange these letters xyz side by side?
There are six different ways to arrange the letters XYZ...
XYZ
XZY
YXZ
YZX
ZXY
ZYX
