Question
How many people have birthdays before
S? Study the following information carefully and answer the given questions. Eight persons M, N, O, P, Q, R, S and T have their birthdays on different months of the year viz. January, April, May and July, such that not more than two persons have their birthdays in the same months. All the birthdays are either on 14th or 23rd of the month. No two persons have their birthdays on the same day of the same month. The following information is also known about them. R does not have birthday in May. Q wasn’t born in July. T’s birthday is immediately after N’s. Q celebrates his birthday before N. The number of persons who have their birthdays between the birthdays of S and T is equal to the number of persons who have their birthdays between the birthdays of N and P. P was born in July. Birthdays of both Q and N are in the same month. There are three birthdays between the birthdays of R and O. S celebrates his birthday before T.Solution
P was born in July. Q’s birthday is before N. Q wasn’t born in July. Birthdays of both Q and N are in the same month. Therefore, both Q and N may have their birthdays in January, April or May. 
T’s birthday is immediately after N’s. The number of persons who have their birthdays between the birthdays of S and T is equal to the number of persons who have their birthdays between the birthdays of N and P. If N’s birthday is on 23 rd May or on 23 rd January, then as shown in figure, the condition of the equal no. of birthdays between S and T, and N and P won’t be met.(refer to the below table) 
The number of persons who have their birthdays between the birthdays of S and T is equal to the number of persons who have their birthdays between the birthdays of N and P. R does not have birthday in May. There are three birthdays between the birthdays of R and O. Now there are two possible dates for P’s birthday u.q. 14th July and 23rdJuly. First let us assume P's birthday on 14th July- 
But, the condition that there are three birthdays between the birthdays of R and O wouldn’t be met in the above arrangement. Therefore, assuming P’s birthday is on 23rd July and redrawing the table, we get- 
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