Reasoning Ability - Calendar Problems
If 1st January 1999 was Friday, what day was 1st January 2005?
If 1st January 1999 was Friday, what day was 1st January 2005?
hard Q10 of 15
Step-by-Step Solution
Step 1: Years crossed
From 1 Jan 1999 → 1 Jan 2005 we cross the years 1999, 2000, 2001, 2002, 2003, 2004.Step 2: Odd-day contributions
1999 = ordinary → 1; 2000 = leap (divisible by 400) → 2; 2001 = ordinary → 1; 2002 = ordinary → 1; 2003 = ordinary → 1; 2004 = leap → 2. Total = 1 + 2 + 1 + 1 + 1 + 2 = 8 odd days.Step 3: Reduce modulo 7
8 mod 7 = 1 → net shift = +1 day.Step 4: Apply shift
Base weekday = Friday. Friday + 1 = Saturday.Final Answer:
Saturday → Option AQuick Check:
Total odd days 8 → 1 shift → Friday → Saturday ✅
Quick Trick: Sum odd days across crossed years (ordinary = 1, leap = 2), reduce mod 7, then shift the weekday.
Common Mistakes:
MISTAKES- Forgetting to include century leap years like 2000 or mis-reducing modulo 7.
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