IMC 2016 Q4
4. Amrita is baking a cake today. She bakes a cake every fifth day. How many days will it be before she next bakes a cake on a Thursday?
- A 5
- B 7
- C 14
- D 25
- E 35
Intermediate Mathematical Challenge 2016, Question 4. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: E 35
Amrita bakes every 5 days and Thursdays come every 7 days. So the next time Amrita bakes on a Thursday will be in 35 days time since 35 is the lowest common multiple of 5 and 7.
Solution © UK Mathematics Trust, from the IMC 2016 solutions. Longer versions with investigations: Solutions and investigations (PDF).