Question: How long did the ten plagues last?
Answer: According to the Mishnah (Eduyos 2:10), the punishment of the Egyptians lasted for 12 months. This implies about a month for each plague; some say that each plague lasted for a week and was preceded by a three-week warning, and some say the reverse. According to both of these views, the time between the first and tenth plagues (inclusive) was at least ten months. But others say that the plagues lasted for only about 10 weeks. In fact, the Torah says that the first plague lasted seven days (Ex.7:25), and some of the plagues lasted less than seven days; the darkness lasted three days (Ex.10:23), and the firstborn died at midnight of one night.