MathDB
2022 B Individual #23

Source:

April 30, 2022
2022 B Individual

Problem Statement

Friends Alice, Betty, and Cathy are playing a game. Betty and Cathy are each given a square number, such that Betty knows Cathy's number and Cathy knows Betty's, but neither of them know their own.
Alice then says: "The sum of the numbers is less than 100." Betty says: "If Cathy knew the number of possibilities for my number, she would know her own." Cathy then says: "Now I know my number."
What is Cathy's number?
<spanclass=latexbold>(A)</span>16<spanclass=latexbold>(B)</span>25<spanclass=latexbold>(C)</span>36<spanclass=latexbold>(D)</span>49<spanclass=latexbold>(E)</span>64<span class='latex-bold'>(A) </span>16\qquad<span class='latex-bold'>(B) </span>25\qquad<span class='latex-bold'>(C) </span>36\qquad<span class='latex-bold'>(D) </span>49\qquad<span class='latex-bold'>(E) </span>64