Mathematics and Stastics

 Data Sufficiency in Statistics A sufficient statistic is a statistic that summarizes all of the information in a sample about a chosen parameter. For example, the sample mean, x̄, estimates the population mean, μ. x̄ is a sufficient statistic if it retains all of the information about the population mean that was contained … Read more

 BOAT AND STREAM Boat and stream problems is a sub-set of time, speed and distance type questions where in relative speed takes the foremost role. We always find several questions related to the above concept in SSC common graduate level exam as well as in bank PO exam. Upon listing … Read more

 Contribution of aryabhatta in mathematics Number notation Numerical values He made a notation system in which digits are denoted with the help of alphabet numerals e.g., 1 = ka, 2 = Kha, etc. Aryabhatta assigned numerical values to the 33 consonants of the Indian alphabet to represent 1,2,3…25,30,40,50,60,70,80,90,100. Notation system  He invented a … Read more

 TIME AND WORK In these problems the number of persons, quantity of work done and time taken are important factors. Also time taken by a person depends on the efficiency of that person which comes into picture when different people do the work such as women, children do the work … Read more

   TIPS AND TRICKS FOR SPEEDY CALCULATIONS – MODULE III – MULTIPLICATION In this module we deal with techniques using which we can multiply two numbers in an unorthodox but quick manner. Firstly we take up some specific cases using which we come to generalized multiplication of any two given numbers. Multiplying two … Read more

 MATHEMATICS AND QUATITUATIVE APTITUDE – SIMPLE INTEREST Introduction Money is not free and it costs to borrow the money. Normally, the borrower has to pay an extra amount in addition to the amount he had borrowed. i.e, to repay the loan, the borrower has to pay the sum borrowed and the interest. Lender … Read more

 Age Problems   Important Formulas on “Problems on Ages”:   1. If the current age is x, then n times the age is nx. 2. If the current age is x, then age n years later/hence = x + n. 3. If the current age is x, then age n years ago = x – n. 4. The ages in a ratio a : b will be ax and bx. 5. If the current age is x, … Read more

          Important Formulas – Percentage Percentage Percent means for every 100 So, when percent is calculated for any value, it means that we calculate the value for every 100 of the reference value. percent is denoted by the symbol %. For example, x percent is denoted by x% x%=x/100 Example : … Read more

 Simplification Simplification is one of the most important part of Quantitative Aptitude section of any competitive exam. Today I am sharing all the techniques to solve Simplification questions quickly. Rules of Simplification V → Vinculum B → Remove Brackets – in the order ( ) , { }, [ ]  O → Of D → Division M … Read more

 Square Root & Cube Root   Step 1: First of all group the number in pairs of 2 starting from the right.   Step 2: To get the ten’s place digit, Find the nearest square (equivalent or greater than or less than) to the first grouped pair from left and put the square root of the … Read more