NIELIT Scientist B 2020 November: 23

Question

 

If $09/12/2001(DD/MM/YYYY)$ happens to be Sunday, then $09/12/1971$ would have been a:

• A. Wednesday
• B. Tuesday
• C. Saturday
• D. Thursday

Answer 1

30 years gap with 8 leap years( 72,76,80,84,88,92,96,2000)  

in every year 1 day is forwarded  365 mod 7 =1

in every leap year 1 extra day is forwarded 366 mod 7 =1

so total days difference 30+8 =38 days

38 mod 7 =3 so 3 days are forwarded from 9/12/71 to 9/12/01

hence it was Thursday ( 3 days backward) on 9/12/71  since it was Sunday  9/12/01