Riddle:
A car thief, who had managed to evade the authorities in the past, unknowingly took the automobile that belonged to Detective Anderson. The detective wasted no time and spared no effort in discovering and carefully examining the available clues. He was able to identify four suspects with certainty that one of them was the culprit.
The four make the statements below. From twelve of total statements, six are true and six false.
Suspect A:
1. C and I have met many times before today.
2. B is guilty.
3. The car thief did not know it was the Detective's car.
Suspect B:
1. D did not do it.
2. D's third statement is false.
3. I am innocent.
Suspect C:
1. I have never met A before today.
2. B is not guilty.
3. D knows how to drive.
Suspect D:
1. B's first statement is false.
2. I do not know how to drive.
3. A did it.
Which one is the car thief?
Show Answer
Answer:
Let's say 6 statements are lies.
A's 1st statement and C's 1st statement negate each other. One of them is a lie.
C's and D's negate each other. One of them is lying. Therefore, there are 4 additional false statements.
Assume A is guilty. If so, A's second statement, B's second statement, and D's first statement are the additional lies.
Assume D is guilty. If so, A's second statement, B's first statement, and D's third statement are lies. This also only makes five false statements. D did not do it.
Assume C did it. If so, A's second statement, D's first and third statements are false. This again, makes only five false statements.
After ruling out suspects A, C and D, B is the culprit. B's third statement, C's second statement, and D's first and third statements are the additional false statements. This adds up to
six.