Log in 😊 8 years agoPosted 8 years ago. Direct link to 😊's post “how do I calculate the pr...” how do I calculate the probability of a z-score? • (19 votes) Piquan 8 years agoPosted 8 years ago. Direct link to Piquan's post “That's a great question! ...” That's a great question! Fortunately, the next set of lessons, at https://www.khanacademy.org/math/statistics-probability/modeling-distributions-of-data/normal-distributions-library/v/ck12-org-normal-distribution-problems-qualitative-sense-of-normal-distributions , discuss exactly that. It's great that you're thinking ahead! (26 votes) Nick Leshuk 8 years agoPosted 8 years ago. Direct link to Nick Leshuk's post “how do you calculate the ...” how do you calculate the mean when you are only given the z-scores? • (5 votes) RacheLee 8 years agoPosted 8 years ago. Direct link to RacheLee's post “To calculate the mean, yo...” To calculate the mean, you need to know z-scores, the data, and the standard deviation. (14 votes) Tou 6 years agoPosted 6 years ago. Direct link to Tou's post “how do you calculate this...” how do you calculate this: µ=10 and σ =1, P(X>10) • (6 votes) Shaghayegh 4 years agoPosted 4 years ago. Direct link to Shaghayegh's post “Is it necessary to assume...” Is it necessary to assume the distribution is normal? • (3 votes) loumast17 4 years agoPosted 4 years ago. Direct link to loumast17's post “to use z scores. If not,...” to use z scores. If not, or you do not know the population standard deviation you would use a different kind of score called the t score For z scoreyou need both the population standard deviation and for the sample to be greater than 30. There are other aspects in statistics where having a normal distribution is necessary. (6 votes) 1315031658 7 years agoPosted 7 years ago. Direct link to 1315031658's post “How do you find the data ...” How do you find the data when you have the mean, the z-score, and the standard deviation? • (2 votes) Ian Pulizzotto 7 years agoPosted 7 years ago. Direct link to Ian Pulizzotto's post “Let x represent the data ...” Let x represent the data value, mu represent the mean, sigma represent the standard deviation, and z represent the z-score. So the data value equals the z-score times the standard deviation, plus the mean. Have a blessed, wonderful day! (7 votes) sebastian grez 8 years agoPosted 8 years ago. Direct link to sebastian grez's post “what happens when you get...” what happens when you get the number of X-U/standar desviation ahd you get a number above 3, that number will not be in the tabla of Z • (4 votes) psthmn 7 years agoPosted 7 years ago. Direct link to psthmn's post “You could try to find a m...” You could try to find a more extensive Z table, for example here: http://www.intmath.com/counting-probability/z-table.php But at a certain point the difference in probality at changing z values gets vanishingly small, so it doesn't really matter what the actual value at that point is. If you are faced with this situation, in most cases P > P(Z=3) is a useful and sufficient answer. (1 vote) Bryan 4 years agoPosted 4 years ago. Direct link to Bryan's post “Are z-scores only applica...” Are z-scores only applicable for normal distributions? You could describe how many standard deviations far a data point is from the mean for any distribution right? But is the term z-score only for normal dists? • (3 votes) Rebecca 4 years agoPosted 4 years ago. Direct link to Rebecca's post “The z-score could be appl...” The z-score could be applied to any standard distribution or data set. It definition only depends on the (arithmetic) mean and standard deviation, and no other qualitative properties of the nature of the data set. (2 votes) Samael Pena 5 years agoPosted 5 years ago. Direct link to Samael Pena's post “What if I don't have the ...” What if I don't have the score but only the Z score. How can I calculate what the score is • (3 votes) muhammad fajar rizqi 6 years agoPosted 6 years ago. Direct link to muhammad fajar rizqi's post “Hello Everybody, I want t...” Hello Everybody, I want to ask, how to calculate that has z-score is more than 3 or -3? because sometimes i calculate the z-score and can't get the result because it's out of range from the z-table. Thank you • (3 votes) Rosivette Andrade 5 years agoPosted 5 years ago. Direct link to Rosivette Andrade's post “Would anyone mind explain...” Would anyone mind explaining this ? A. about 2 • (2 votes)Want to join the conversation?
z-score=(data-mean)/standard deviation
data-mean=(z-score)(standard deviation)
mean=(data)-(z-score)(standard deviation)
Since the z-score is the number of standard deviations above the mean, z = (x - mu)/sigma.
Solving for the data value, x, gives the formula x = z*sigma + mu.
For a normal distribution of 1000 cases, how many cases will be farther away from the mean than + 3 standard deviations?
B. at least 500
C. it is impossible to estimate
D. 327
FAQs
What is the formula for calculating the z-score? ›
Z Score = (x − x̅ )/σ
Where, x = Standardized random variable. x̅ = Mean. σ = Standard deviation.
A z score is unique to each value within a population. To find a z score, subtract the mean of a population from the particular value in question, then divide the result by the population's standard deviation.
What is the rule of thumb for z-scores? ›Data that is two standard deviations below the mean will have a z-score of -2, data that is two standard deviations above the mean will have a z-score of +2. Data beyond two standard deviations away from the mean will have z-scores beyond -2 or 2.
What is the original z-score formula? ›The original Z-score formula was as follows: Z = 1.2X1 + 1.4X2 + 3.3X3 + 0.6X4 + 1.0X5. X1 = ratio of working capital to total assets. Measures liquid assets in relation to the size of the company.
How to find z-score with mean and percentile? ›1 Answer. Z = (x - mean)/standard deviation. Assuming that the underlying distribution is normal, we can construct a formula to calculate z-score from given percentile T%.
What is the formula for the z-score to P? ›The distribution for z is the standard normal distribution; it has a mean of 0 and a standard deviation of 1. For Ha: p ≠ 26, the P-value would be P(z ≤ -1.83) + P(z ≥ 1.83) = 2 * P(z ≤ -1.83). Regardless of Ha, z = (p̂ - p0) / sqrt(p0 * (1 - p0) / n), where z gives the number of standard deviations p̂ is from p0.
What is the formula for z-score for a child? ›Based on body mass Index (BMI)
Z-score and percentile equivalence: 3SD=0.1%; 2SD=2.3%; 1SD=15.9%; +1SD=84.1%; +2SD=97.7%; +3SD=99.9%.
To calculate the critical z value for any confidence level, look for 1−α/2 value in the z table. For the 95% level, look for 0.975, not 0.95, to note the value of 1.96. Similarly, for 90% and 99% confidence levels, the critical z values are 1.645 and 2.575, respectively.
What is the z-score for 95 confidence interval? ›The Z value for 95% confidence is Z=1.96.
How are z-scores calculated? ›The formula for calculating a z-score is z = (x-μ)/σ, where x is the raw score, μ is the population mean, and σ is the population standard deviation. As the formula shows, the z-score is simply the raw score minus the population mean, divided by the population standard deviation.
What are the two z-score formulas? ›
The z score for a datum x is z=(x−μ)/σ where μ is the population mean and σ is the population standard deviation. If the datum x is not from the entire population but rather from a sampling from that population then the standard deviation is divided by the square root of the sample size n.
What is the formula for z-score in Excel? ›The formula for computing a z-score is =(DataValue-Mean)/StDev. For example, to compute a z- score for the first value in our data set, we use the formula =(A2-$D$2)/$E$2 as Figure 1 illustrates. Notice the dollar signs $ in the formula.
What is the formula for the z value in the z test? ›If x̅ is the sample mean, μ0 is the population mean, σ is the standard deviation, and n is the sample size, then the z-trial formula is expressed as follows: Z = (x̅ – μ0) / (σ /√n).
What is the formula for the Z table? ›Solution: To find the z-score, we use the formula: z = (x - mean) / standard deviation. Plugging in the values, we get: z = (70,000 - 50,000) / 10,000 = 2 The z-score for a participant who earns $70,000 is 2, which means that this participant's income is 2 standard deviations above the mean income of the group.