Cheryl And Betty Celebrate
Logic
Level
3
One day, Cheryl and Betty list down possibilities for their birthday dates.
By some strange coincidence, they wrote the same possibilities for their birthday dates.
They were
| Jun 4 | Jun 6 | Jun 8 | |
| Jul 4 | Jul 5 | Jul 6 | Jul 8 |
| Aug 4 | Aug 5 | Aug 7 | Aug 9 |
| Sep 3 | Sep 5 | Sep 7 | Sep 10 |
Cheryl then told Betty the day of month of her birthday.
Betty told Cheryl the month of her birthday.
Cheryl: "I know that Betty does not know my birthday."
Betty: "Cheryl does not also know my birthday and my birthday is not on Sep 5."
Cheryl: "You gave me redundant information and my birthday is not on Aug 7."
Betty: "Now I know your birthday and the day of the month of my birthday is a prime number."
Cheryl: "Now I know your birthday."
What is the difference (in days) between Betty's and Cheryl's birthday? (both dates inclusive).
by
Joel Yip