Question 18 (Textile Engineering & Fibre Science)
If the length of a confidence interval on the mean of a normal distribution with known variance is to be halved, the sample size must
| (A) | increase by 2 times |
| (B) | decrease by 2 times |
| (C) | increase by 4 times |
| (D) | decrease by 4 times |
[Show Answer]
Confidence interval(C.I.) is directly proportional to standard error.
and
Standard error(S.E.)=
Where, n is sample size
Given, 
n2=4 x n1
Frequently Asked Questions | FAQs
What is the mean of normal distribution?
The mean of a normal distribution is a measure of central tendency and represents the center of the distribution. In a normal distribution, the mean is also the peak of the distribution and is often denoted by the Greek letter μ (mu).
For example, if we have a normal distribution with a mean of 50, it means that the data is centered around 50, and the highest point of the bell-shaped curve is at 50. The mean of a normal distribution is also the expected value or the average value of the random variable that follows this distribution.
In addition, the normal distribution is a symmetric distribution, so the mean is also the median and the mode of the distribution. This means that 50% of the data falls below the mean, and 50% of the data falls above the mean.
The mean of a normal distribution can be calculated using the formula:
μ = (Σx) / n
where μ is the mean, Σx is the sum of all the values in the distribution, and n is the number of values in the distribution. However, in practice, we often use statistical software or calculators to calculate the mean of a normal distribution.