Section: Arithmetic Reasoning

4) If a patient doesn't receive treatment for a certain injury within 2 hours after injury, the patient's chance of survival starts decreasing by 15% each hour. If no treatment has been given within 4 hours after injury, roughly, what chance of survival will the patient have?

1. 70%
2. 72%
3. 75%
4. 77%
5. 80%