( ) for x = , , , ..., are given by Estimate the value of y ( . ) using forward interpolation formula by choosing the four values that will give the best approximation. Since we apply the forward interpolation formula,last four values of f x ( ) are taken into consideration (Take the values from x = ). The forward interpolation formula is n n x x nh !
, ∴ n = The difference table is D y D y D y y x = . = = Example . From the following table find the number of students who obtained marks less than . Marks - - - - - No.
of Students Let x be the marks and y be the number of students. By converting the given series into cumulative frequency distribution, the difference table is as follows. D y D y D y D y Less than – - - XII Std - Business Maths & Stat EM Chapter - - Numerical Methods n n x x nh ! !
n n )( ! ... To find y at x = ∴ nh , ⇒ n = y x = =