1. In the year 2000, the average salaries of elementary school teachers in Oregon, Washington and Alaska were (in thousands USD) 40.9, 41.1 and Given that there were 19.7, 28.1 and 5.3 thousand teachers in these states. Find the average salary of all the elementary school teachers in the three states.

2. A wholesaler sold 575, 410 and 520 microwave ovens at prices (in USD) 75, 125 and 100 respectively. What is the mean price of the ovens sold?

3. If somebody invests TL 1,000 at 7%, TL 3,000 at 7
If somebody invests TL 1,000 at 7%, TL 3,000 at 7.5% and TL 16,000 at 8%.
What is the overall percentage yield of these investments?

4. The number of employees of the municipalities in a certain area of a country were given in the following table
Find the mean and modal class? #
Frequency 2 7 16 26 18 4

5. THE MODE
- If a data set has only one value that occurs with greatest frequency is said to be UNIMODAL
If a data set has two values that occur with the same greatest frequency is said to be BIMODAL
If a data set has more than two values that occur with the same greatest frequency, each value is used as the mode, and the data set is said to be MULTIMODAL
When no data value occurs more than once, the data set is said to have NO MODE

6. Example:
The following data represent the duration (in days) of Space Shuttle voyages for the years (18 values)
8,9,9,14,8,8,10,7,6,9,7,8,10,14,11,8,14,11
Q: Find The Mode

7. MONTHLY STARTING SALARY (In TRL)
Graduate
Monthly Starting Salary 1
2,850 2
2,950 3
3,050 4
2,880 5
2,755 6
2,710 7
2,890 8
3,130 9
2,940 10
3,325 11
2,920 12
TOTAL: ,280

8. Properties of the Mean
1- The Mean can be calculated for any set of NUMERICAL Data
2- The Mean is unique and unambiguous value.
3- The means of several sets of data can always be combined into the overall mean of all the data.
4- If each value in a sample were replaced by the mean, then ∑X would remain unchanged
5- The mean takes into account the value of each item in a set of data.
6- The mean is relatively reliable in the sense that means of many samples drawn from the same population generally do not fluctuate, or vary, as widely as other statistics used to estimate the mean of a population.

9. Properties of the Median
In addition to the properties of the Mean;
1- It splits the data into two parts
2- The median is preferable to the mean because it is not so easily affected by extreme values.

11. Problem: The following list gives the duration in minutes of 24 power failures.
Find the median.