Riddle: Three working women have different careers. If only one of statements 1, 2 and 3 are true, can you tell whether or not Mary is a nurse? 1. This statement is only true if statement 5 is false. 2. This statement is true if statements 4 or 5, or both 4 and 5 are true. 3. This statement is false only if both statements 6 and 1 are true. 4. Mary is a nurse 5. Karen is an artist. 6. Sarah is a photographer.
Answer: Mary is not a nurse. The way to solve this riddle, is to consider statements 4, 5, and 6 and create a chart of all possible true and false answers. Next, fill in the chart according to statements 1 through 3. You will discover that there is only one line where only one of statements one, two and three are true. Thus, it is determined that: Statement 4 and 5 are false and statement 6 is true.