रसिला बहुत करून तिच्या भावाला त्यांच्या स्थानिक रेल्वे स्थानकात संध्याकाळी 5.56 वाजता भेटते आणि तो तिला त्यांच्या घरी घेऊन येतो. एके दिवशी तिने तिची कचेरी लवकर सोडली आणि ती स्थानकावर संध्याकाळी 4.50 वाजता पोहोचली. ती तिच्या घराच्या दिशेने चालू लागली. वाटेत तिला त्यांच्या घरून येणारा भाऊ भेटला आणि ते घरी नेहमीपेक्षा 20 मिनिटे आधी पोहोचले. तर ती किती वेळ चालली ?

The correct answer is Option D (Cannot be calculated as time required for reaching home is not given).

Key Points:
• Official Answer Key: The official MPSC final answer key gives Option 4 ('Cannot be calculated as time required for reaching home is not given') as the final answer.
• Why option 4 was held valid by MPSC: The problem does not state whether the brother started from home at his usual departure time or when he started; without knowing the brother's departure schedule or one-way travel time, ambiguous assumptions arise.
• Note on standard textbook solution: In standard aptitude problem formulations where the driver starts at his usual time, saving 20 minutes for a round trip means saving 10 minutes each way, meeting her at 5:46 p.m. (walking for 56 minutes). However, MPSC officially declared Option 4 because crucial travel time parameters were not explicitly specified in the question text.
• Key Takeaway: MPSC official key finalized Option 4 because requisite home travel time was not provided.