An hour -long test has 60 problems. If a student completes 30 problems in 25 minurtes. Then the required seconds he has taken on average for computing each of the remaining problems is

Options

A. 70 seconds
B. 50 seconds
C. 40 seconds
D. 30 seconds

Answer

To solve the problem step by step, we will follow these calculations:

1. **Identify the total time available for the test**:
The test duration is 1 hour, which is equal to 60 minutes.

2. **Calculate the time remaining after completing 30 problems**:
The student has completed 30 problems in 25 minutes. Therefore, the remaining time is:
\[ \text{Remaining time} = 60 \text{ minutes} - 25 \text{ minutes} = 35 \text{ minutes} \]

3. **Convert the remaining time into seconds**:
Since we need the average time per problem in seconds, we convert the remaining time from minutes to seconds:
\[ \text{Remaining time in seconds} = 35 \text{ minutes} \times 60 \text{ seconds/minute} = 2100 \text{ seconds} \]

4. **Determine the number of problems remaining**:
The total number of problems is 60, and the student has completed 30 problems, so the number of problems left is:
\[ \text{Remaining problems} = 60 - 30 = 30 \text{ problems} \]

5. **Calculate the average time taken per remaining problem**:
To find the average time taken for each of the remaining problems, we divide the total remaining time in seconds by the number of remaining problems:
\[ \text{Average time per problem} = \frac{\text{Remaining time in seconds}}{\text{Remaining problems}} = \frac{2100 \text{ seconds}}{30 \text{ problems}} = 70 \text{ seconds/problem} \]

Thus, the required average time taken for computing each of the remaining problems is **70 seconds**.