Question

Ranjit and Radhika got married on Friday, $\text{25 January 1980}$. they decided to go to a picnic spot and enjoy the whole day on their wedding anniversary, each year, provided it does not fall on either Monday or Wednesday. On how many occasions during the next $10$ years did they visit the picnic spot on heir wedding anniversary ?

Answer 1

Let us calculate the day on each of the 25th January till next 10 years.
a) 25 Jan 1980 - 25 Jan 1981 period consists of a Leap year having 2 odd day. Therefore, 25 Jan 1981 is Sunday.
b) 25 Jan 1981 - 25 Jan 1982 period consists of a non-leap year having 1 odd day. Therefore, 25 Jan 1982 is Monday.
c) 25 Jan 1982 - 25 Jan 1983 period consists of a non-leap year having 1 odd day. Therefore, 25 Jan 1983 is Tuesday.
d) 25 Jan 1983 - 25 Jan 1984 period consists of a non-leap year having 1 odd day. Therefore, 25 Jan 1984 is Wednesday.
e) 25 Jan 1984 - 25 Jan 1985 period consists of a leap year having 2 odd day. Therefore, 25 Jan 1985 is Friday.
f) 25 Jan 1985 - 25 Jan 1986 period consists of a non-leap year having 1 odd day. Therefore, 25 Jan 1986 is Saturday.
g) 25 Jan 1986 - 25 Jan 1987 period consists of a non-leap year having 1 odd day. Therefore, 25 Jan 1987 is Sunday.
h) 25 Jan 1987 - 25 Jan 1988 period consists of a non-leap year having 1 odd day. Therefore, 25 Jan 1988 is Monday.
i) 25 Jan 1988 - 25 Jan 1989 period consists of a leap year having 2 odd days. Therefore, 25 Jan 1989 is Wednesday.
j) 25 Jan 1989 - 25 Jan 1990 period consists of a non-leap year having 1 odd day. Therefore, 25 Jan 1990 is Thursday.
Clearly, in the next 10 years they will go 6 times to a picnic spot on their wedding anniversary.