This quantity is approximated via the convergence of iteratively reweighted least squares in Weiszfeld’s algorithm. In image processing, salt-and-pepper noise is effectively reduced by a nonlinear filter named for this quantity. Two subproblems have size one-fifth n and seven-tenths n in the recurrence of an algorithm that computes this quantity. Using two heaps computes this quantity for a stream input in a problem about its “maintenance.” This quantity appears twice in the name of a (*) pivot-finding algorithm that (10[1])runs in asymptotically worst-case linear time. The optimal runtime of quicksort occurs (10[1])when the pivot always equals this value of the subarray. One way to find (10[1])this quantity is to sort an array and get the element at index closest to half the array length. For 10 points, name this quantity equal to the 50th percentile of a data set. ■END■