A class starts at 10 a.m. and lasts till 1.27 p.m. Four periods are held during this interval. After every period, 5 minutes are given free to the students. The exact duration of each period is

### Concept & Logic\n\nTo find the exact duration of a single period, determine the total duration of the school session, subtract the total interval time allocated for breaks, and divide the remaining time equally by the number of periods.\n$$\\text{Total Period Time} = \\text{Total Duration} - \\text{Total Break Time}$$\n\n### Step-by-Step Solution\n\n* **Calculate Total Duration:**\n From 10:00 a.m. to 1:27 p.m. is 3 hours and 27 minutes.\n $$\\text{Total minutes} = (3 \\times 60) + 27 = 180 + 27 = 207 \\text{ minutes}$$\n\n* **Calculate Total Break Time:**\n There are 4 periods. Breaks occur *between* periods. Therefore, there are exactly 3 breaks (after the 1st, 2nd, and 3rd periods).\n $$\\text{Total break time} = 3 \\times 5 = 15 \\text{ minutes}$$\n\n* **Calculate Duration of Each Period:**\n $$\\text{Time for periods} = 207 - 15 = 192 \\text{ minutes}$$\n $$\\text{Duration of one period} = \\frac{192}{4} = 48 \\text{ minutes}$$\n\n### Exam Strategy & Shortcut\n\nBe absolutely precise on the number of breaks: $N$ periods arranged linearly will always have exactly $N - 1$ breaks between them. Once you arrive at 192 minutes, a quick glance at the options shows that $4 \\times 50 = 200$, so the answer must be slightly less than 50, pointing directly to 48.\n\n### Common Pitfall\n\nMany students assume there are 4 breaks for 4 periods, calculating $4 \\times 5 = 20$ minutes of free time. This leads to $207 - 20 = 187$, which is not cleanly divisible by 4, causing confusion and wasted time.\n\n### Final Answer\n\n**Therefore, the correct answer is 48 minutes.**