STATEMENT OF THE "SIMPLE PROBLEM" THAT "BAFFLES A NATION!"
In 1951 I found a book, Facts Into Figures, by F. J. Moroney, a British communication engineer. Moroney stated the following problem, which I solved incorrectly by the standard response.

A flier in a "prop" plane is flying a square course, 100 miles on a size.
He flies the first 100-mile course, W-E, at an averags epeed of 100 mph.
He fliies the sccond 100-mile course, N-S, at an average speed of 200 mph.
He fliies the third 100300 mph. He fliies the fourth (and final) 100-mile course, S-N, at an average speed of 200 mph, to complete the square-course.
Problem: WHAT IS THE AVERAGE SPEED FOR THE ENTIRE SQUARE-COURSE?
PLEASE NOTICE! Solution of this problem requires only ADDITION, SUBTRACTION, MULTIPLICATION, DIVISION, all subjects introduced by FIFTH GRADE studies!