May 2012
Problem of the Month

The Puzzled Driver



The odometer of the family car shows 15,951 miles.
The driver noticed that this number is palindromic:
It reads the same backward as forward.

"Curious," the driver said to himself, "It will be a long time before that happens again."
But two hours later, the odometer showed a new palindromic number.

How fast was the car traveling in those two hours?
You may assume that the driver does not go over 100 mph!



Solution to the Problem:

The driver was going 55 mph.

The first digit of 15951 could not change in two hours.
Therefore, 1 is the first and last digit of the new number.
The second and fourth digits changed to 6.
The middle digit could be 0, 1, 2, 3, ... 9.
So, the miles driven would be 110, 210, 310, ... respectively.
In two hours, the car would have gone at a speed of 55 mph, 105 mph, 155 mph, ... respectively.



Correctly solved by:

1. James Alarie Flint, Michigan
2. Alp Aribal Istanbul, Turkey
3. Dakota Rees Mountain View High School,
Mountain View, Wyoming
4. Chad Fore Gate City, Virginia
5. Brandon Cheng Farmington High School
Farmington, Connecticut
6. Rachel Hofer Mountain View High School,
Mountain View, Wyoming
7. Matt Zadra Mountain View High School,
Mountain View, Wyoming
8. David & Judy Dixon Bennettsville, South Carolina
9. Matt Hale Mountain View High School,
Mountain View, Wyoming
10. Cassie Warren Mountain View High School,
Mountain View, Wyoming
11. Alexis Condos Mountain View High School,
Mountain View, Wyoming
12. Riley Dolezal Mountain View High School,
Mountain View, Wyoming
13. Aubrey Newton Mountain View High School,
Mountain View, Wyoming
14. Karsten Hauf Mountain View High School,
Mountain View, Wyoming
15. John C. Funk Ventura, California
16. Alex Snyder Mountain View High School,
Mountain View, Wyoming
17. Alyssa Sibelrud Mountain View High School,
Mountain View, Wyoming
18. Marissa Vitt Mountain View High School,
Mountain View, Wyoming
19. Kalvin Hereford Mountain View High School,
Mountain View, Wyoming
20. Kaylor Dolezal Mountain View High School,
Mountain View, Wyoming
21. Josey Pitts Mountain View High School,
Mountain View, Wyoming
22. Isaac Kampman ----------
23. Michael Brown Mountain View High School,
Mountain View, Wyoming


Send any comments or questions to: David Pleacher