In a certain year, there were exactly four Fridays and four Mondays in January. On what day of the week did the 20th of January fall that year?
Explanation
Step 1: Identify which days occur 5 times
The problem states there are exactly four Fridays and four Mondays.
This implies that neither Friday nor Monday can fall on the 1st,2nd, or 3rd of January.
Step 2: Determine the sequence of days
Let's look at the days between Monday and Friday: Tuesday, Wednesday, and Thursday.
If these three days are the ones that occur 5 times, then:
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1st January = Tuesday
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2nd January = Wednesday
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3rd January = Thursday
If the 1st is a Tuesday, then the 31st (last day) will also be a Thursday (1+30 days, where 30÷7 leaves a remainder of 2, so Tuesday +2=Thursday). In this scenario:
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Mondays: 7,14,21,28 (Total 4) — Matches condition.
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Fridays: 4,11,18,25 (Total 4) — Matches condition.
Step 3: Calculate the 20th of January
Since the 1st of January is a Tuesday:
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1st = Tuesday
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8th = Tuesday
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15th = Tuesday
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15+5=20th
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Tuesday +5 days=Sunday
Conclusion:
The 20th of January falls on a Sunday.
Correct Option: (b)