HelpPrepInsta Hello Harshita , “The average of squares of first n natural numbers = (n+1)(2n+1)/6” This is the formula of Arithmetic Progression . Warm Rgards , PrepInsta Team Log in to Reply
srinivas In type2 question why we have to Multiplying (1) by 12 and subtracting from (2) Log in to Reply
Vaibhav Jain In this type of questions we form 2 quadratic equations and try to solve them for calculating the desired answer. So in the process of solving those quadratic equations, we need to make atleast one of the variable equal in both the equation, that is the reason why we multiplied eq 1 by 12 Log in to Reply
Ashish Mishra Hi Prepkumar, It is already given in the question that when train move by stopping than it speed is 48kmph. And we need to find its average stoppage time. Thank You Log in to Reply