At Srinagar, starting at 9 a.m. on a certain day, snow began to fall at a rate of $1\frac{1}{4}$ inches every two hours until 3 p.m. If there was already $2\frac{1}{4}$ inches of snow on the ground at 9 a.m., how many inches of snow was on the ground at 3 p.m. that day?

### Concept & Logic This problem involves calculating a total accumulation by multiplying a rate over a specific time interval and adding it to an initial baseline quantity. ### Step-by-Step Solution * **Given:** * Initial snow on the ground = $2\frac{1}{4} = 2.25$ inches. * Rate of snowfall = $1\frac{1}{4} = 1.25$ inches per 2 hours. * Time duration (from 9 a.m. to 3 p.m.) = 6 hours. * **Calculation:** First, determine the snowfall per hour: $$\text{Hourly rate} = \frac{1.25}{2} = 0.625 \text{ inches/hour}$$ Next, calculate the total snow fallen during the 6-hour window: $$\text{Total fall} = 6 \times 0.625 = 3.75 \text{ inches}$$ Finally, add this new accumulation to the initial amount on the ground: $$\text{Total snow} = 2.25 + 3.75 = 6 \text{ inches}$$ ### Exam Strategy & Shortcut Since the rate is given per 2 hours, and 6 hours is exactly three 2-hour intervals, skip the per-hour calculation entirely. Simply multiply the interval rate by the number of intervals: $3 \times 1\frac{1}{4} = 3\frac{3}{4}$ inches. Add this directly to the initial baseline: $2\frac{1}{4} + 3\frac{3}{4} = 6$ inches. This mental math pathway avoids decimal conversions completely. ### Common Pitfall Students often forget to add the initial snow amount ($2\frac{1}{4}$) to the accumulated snowfall, incorrectly choosing option (a) $3\frac{3}{4}$. Always reread the final question line to ensure all starting conditions are factored into the final answer. ### Final Answer **Therefore, the correct answer is 6.**