Evanarais29idn
Answered

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             1.         In a certain year, there were exactly four Fridays and exactly four Mondays in December. On what day of the week did the 25th December fall that year?​

Sagot :

AshNicoleQwncyidn

Answer:

MONDAY OR SUNDAY

Four weeks mean exactly 28 days.

In May there are 3 more days.

Hence 3 consecutive days will appear 5 times.

If the 1st falls on a Tuesday, 4th, 11th, 18th and 25th will be Fridays.

And 7, 14, 21, 28 will be Mondays.

This is the only solution that satisfies your conditions.

So 21st will be a Monday.

More Answer:

  • The 1st, 8th, 15th, 22nd, and 29th days of any month are the same say of the week. Since January has 31 days, if the month starts on a given day, there will be five of those days, and also five of the next two days of the week. Hence January could not have started on Saturday, Sunday or Monday (Otherwise there would be five Fridays). Hence January 1 was a Tuesday, and it is not difficult to see that January 20th was a Sunday.

  • 1st May was a Tuesday and 31st May was a Thursday. Hence, 21st of May fall that year was a Monday.

  • If this May only has 4 Fridays and 4 Mondays, May 1 must not fall on Friday or Monday. If May 1 falls on Saturday or Sunday, it will produce 5 Mondays. If May 1 falls on Wednesday and Thursday, it will produce 5 Fridays. So, May 1 in such year shall fall on Tuesday. Thus, May 21 falls on Monday.

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