Mean Deviation=Sum of Deviations by Number of observations The Deviation here means the difference of the observations from any of the central tendencies. But mostly we take the Deviation from Mean or Median but not from Mode. Before we see more formulas we should see that the need for Mean Deviation is to get more accurate quantity to relate different quantities. Here are the steps for finding Mean Deviation: (a.) MD for Ungrouped Data We derive the desired Central Tendencies. We find the value of mod(x-a) for all x. We use the formula for calculating MD: (b.) MD for Grouped Data Types of Grouped Data Discrete Frequency Distribution Continuous Frequency Distribution   Discrete Frequency Distribution We find the desired Central Tendency by the formulas of basic Statistics. We find the value of mod(x-a) for all frequency and observations. We find the value of f×mod(x-a) for all frequency and observations. We find MD by this formula: For Central...

SEQUENCE A collection of numbers arranged in a definite order according to some definite rule (rules) is  called a sequence. Each number of the sequence is called a term of the sequence. The sequence is called finite or  infinite according as the number of terms in it is finite or infinite. ARITHMETIC PROGRESSION A sequence is called an arithmetic progression (abbreviated A.P.) if and only if the difference  of any term from its preceding term is constant. A sequence in which the common difference between successors and predecessors will be  constant. i.e. a, a+d,a+2d This constant is usually denoted by ‘d’ and is called common difference. NOTE : The common difference ‘d’ can be positive, negative or zero. SOME MORE EXAMPLES OF A PARE (a) The heights (in cm) of some students of a school standing in a queue in the morning  assembly are 147, 148, 149, ….. , 157. (b) The minimum temperatures (in degree celsius) recorded for a week in the month of J...

ARITHMETIC PROGRESSION A sequence is called an arithmetic progression (abbreviated A.P.) if and only if the difference of any term from its preceding term is constant. A sequence in which the common difference between successors and predecessors will be constant. i.e. a, a+d,a+2d This constant is usually denoted by ‘d’ and is called common difference. NOTE :  The common difference ‘d’ can be positive, negative or zero.

Quadratic Equation and its Solution "Quadratic Equation is an equation in which the highest power of x is 2" . By this statement I mean to say that the quadratic equations look like this   ax 2 +bx+c=0. Here x has the highest power 2. Finding the solution of the equation means that the value of x for which it satisfies the equation. So when the value of x gives zero as solution then it is called Zero or Root of the equation. For example, if we find the solution of this equation then the value will be called the zero or root of the equation  ax 2 +bx+c=0.