If it was a Friday on 1 January 2016, what was the day of the week on 1 January 2017?

Sunday

The correct answer is Option (4) → Sunday

To determine the day of the week on 1 January 2017, we need to calculate the number of odd days between the two dates.

1. Check for a Leap Year

The year 2016 is a leap year because it is divisible by 4.

• A non-leap year (365 days) has $365 \div 7 = 52$ weeks and 1 odd day.
• A leap year (366 days) has $366 \div 7 = 52$ weeks and 2 odd days.

2. Identify the Extra Day

Since we are moving from 1 January 2016 to 1 January 2017, we pass through February 29, 2016. This means we must account for the leap day.

3. Calculate the New Day

• Start Date: 1 January 2016 (Friday)
• Total Days to 1 January 2017: 366 days (because 2016 is a leap year)
• Odd Days: $366 \div 7$ leaves a remainder of 2.

To find the new day, add 2 days to the starting day:

$\text{Friday} + 2 \text{ days} = \text{Sunday}$