Question 30
Optional bonus question. Printed source scoring: correct +20, incorrect −7, blank 0.
Answer-format rule printed in the source: round a non-integer answer to the nearest integer. If a calculated answer has more than five digits, write its last five digits.
Mark writes a row of four distinct digits chosen from 0 to 9. John guesses, and Mark reports (i) how many guessed digits occur in the row, and (ii) how many occupy the correct positions. For example, if the row is 2561 and the guess is 2018, two digits (2 and 1) are right, but only one position (the first) is right. The five guesses are:
1. 1234: 1 right digit, 1 right position
2. 5678: 1 right digit, 1 right position
3. 9012: 3 right digits, 0 right positions
4. 0926: 2 right digits, 1 right position
5. 1950: 3 right digits, 3 right positions
What row did Mark write?
Answer-format rule printed in the source: round a non-integer answer to the nearest integer. If a calculated answer has more than five digits, write its last five digits.
Mark writes a row of four distinct digits chosen from 0 to 9. John guesses, and Mark reports (i) how many guessed digits occur in the row, and (ii) how many occupy the correct positions. For example, if the row is 2561 and the guess is 2018, two digits (2 and 1) are right, but only one position (the first) is right. The five guesses are:
1. 1234: 1 right digit, 1 right position
2. 5678: 1 right digit, 1 right position
3. 9012: 3 right digits, 0 right positions
4. 0926: 2 right digits, 1 right position
5. 1950: 3 right digits, 3 right positions
What row did Mark write?