The estimated standard deviation goes down as the sample size increases. Also, the degrees of freedom increase and, as they increase, the t-distribution gets closer to the Normal distribution.
It approaches a normal distribution.
Because as the sample size increases the Student's t-distribution approaches the standard normal.
Because t-score isn't as accurate as z-score, you should use 40 as a safety sample size, rather than 30 as you would for a z-score.
z=(x-mean)/(standard deviation of population distribution/square root of sample size) T-score is for when you don't have pop. standard deviation and must use sample s.d. as a substitute. t=(x-mean)/(standard deviation of sampling distribution/square root of sample size)
When you don't have the population standard deviation, but do have the sample standard deviation. The Z score will be better to do as long as it is possible to do it.
It approaches a normal distribution.
Because as the sample size increases the Student's t-distribution approaches the standard normal.
Because t-score isn't as accurate as z-score, you should use 40 as a safety sample size, rather than 30 as you would for a z-score.
A z-score measures how many standard deviations an individual data point is from the mean of a population, assuming the population standard deviation is known and the sample size is large (typically n > 30). In contrast, a t-score is used when the sample size is small (n ≤ 30) or when the population standard deviation is unknown, relying on the sample's standard deviation instead. The t-distribution, which the t-score utilizes, is wider and has heavier tails than the normal distribution, reflecting more uncertainty in smaller samples. As sample sizes increase, the t-distribution approaches the normal distribution, making z-scores more applicable.
T score is usually used when the sample size is below 30 and/or when the population standard deviation is unknown.
z=(x-mean)/(standard deviation of population distribution/square root of sample size) T-score is for when you don't have pop. standard deviation and must use sample s.d. as a substitute. t=(x-mean)/(standard deviation of sampling distribution/square root of sample size)
The fundamental difference between the t statistic and a z score lies in the sample size and the underlying population variance. The t statistic is used when the sample size is small (typically n < 30) and the population variance is unknown, making it more appropriate for estimating the mean of a normally distributed population. In contrast, the z score is used when the sample size is large or when the population variance is known, as it assumes a normal distribution of the sample mean. Consequently, the t distribution is wider and has heavier tails than the z distribution, reflecting greater uncertainty in smaller samples.
There is not enough information in the question to determine if the t-distribution is the appropriate model to use. If it is, then, with, a sample size of 95 the z-score for the Gaussian distribution is a suitable approximation. The probability is 0.199, approx.
If the sample size is less then 30 use the T table, if greater then 30 use the Z table.
T-score is used when you don't have the population standard deviation and must use the sample standard deviation as a substitute.
a "T" or a "Z" score. A "T" Score if comparing a sample. A "Z" Score when comparing a population. Remember, a population includes all observation, and a sample includes only a random selection of the population.
When you don't have the population standard deviation, but do have the sample standard deviation. The Z score will be better to do as long as it is possible to do it.