the average age of a class of 22students is 21 years. the average age increased by 1 when teacher age includes.what is the age of teacher
Answers
In mathematics and statistics, the arithmetic mean ( /ˌærɪθˈmɛtɪk ˈmiːn/, stress on first and third syllables of "arithmetic"), or simply the mean or the average (when the context is clear), is the sum of a collection of numbers divided by the count of numbers in the collection.[1] The collection is often a set of results of an experiment or an observational study, or frequently a set of results from a survey. The term "arithmetic mean" is preferred in some contexts in mathematics and statistics, because it helps distinguish it from other means, such as the geometric mean and the harmonic mean.
In addition to mathematics and statistics, the arithmetic mean is used frequently in many diverse fields such as economics, anthropology and history, and it is used in almost every academic field to some extent. For example, per capita income is the arithmetic average income of a nation's population.
Average refers to the sum of numbers divided by n. Also called the mean average.
Sums of data divided by the number of items in the data will give the mean average. The mean average is used quite regularly to determine final math marks over a term or semester. Averages are often used in sports: batting averages which means number of hits to number of times at bat. Gas mileage is determined by using averages.
For Example: To find the average of 3, 5 and 7.
Solution
Step 1: Find the sum of the numbers.
3 + 5 + 7 = 15
Step 2: Calculate the total number.
There are 3 numbers.
Step 3: Finding average 15/3 = 5
Sum of elements = average × no. of elements
Example 1: The average of marks obtained by 4 students in a class is 65. Find the sum of marks obtained?
Solution. Here, number of marks obtained = 4
Average = 65
∴ sum of marks obtained = 65 × 4 = 260
Number of elements = average-f-18502.png
Example 2: If the sum of elements and average are respectively 65 and 13, then find the number of elements.
While the arithmetic mean is often used to report central tendencies, it is not a robust statistic, meaning that it is greatly influenced by outliers (values that are very much larger or smaller than most of the values). Notably, for skewed distributions, such as the distribution of income for which a few people's incomes are substantially greater than most people's, the arithmetic mean may not coincide with one's notion of "middle", and robust statistics, such as the median, may provide better description of central tendency.