the variance of 20 observation is 10.24 . find its s.d.
Answers
Answer:
The sample mean is the average and is computed as the sum of all the observed outcomes from the sample divided by the total number of events. We use x as the symbol for the sample mean. In math terms,
where n is the sample size and the x correspond to the observed valued.
Example
Suppose you randomly sampled six acres in the Desolation Wilderness for a non-indigenous weed and came up with the following counts of this weed in this region:
34, 43, 81, 106, 106 and 115
We compute the sample mean by adding and dividing by the number of samples, 6.
34 + 43 + 81 + 106 + 106 + 115
= 80.83
6
We can say that the sample mean of non-indigenous weed is 80.83.
The mode of a set of data is the number with the highest frequency. In the above example 106 is the mode, since it occurs twice and the rest of the outcomes occur only once.
The population mean is the average of the entire population and is usually impossible to compute. We use the Greek letter m for the population mean.
Median, and Trimmed Mean
One problem with using the mean, is that it often does not depict the typical outcome. If there is one outcome that is very far from the rest of the data, then the mean will be strongly affected by this outcome. Such an outcome is called and outlier. An alternative measure is the median. The median is the middle score. If we have an even number of events we take the average of the two middles. The median is better for describing the typical value. It is often used for income and home prices.
Example
Explanation: