Question: In a certain code, 'XYZ' means 'We are friends'. Which letter stands for 'We'?

Statements:

1. 'PYN' means 'They are classmates'.
2. 'ZMS' means 'We love them'.
3. 'PX' means 'Hello friends',

From I, we have: M > V, V > S, V > N ...(i)

From II, we have: Mukul is the oldest ...(ii)

From III, we have: S > N ...(iii)

Combining (i) and (iii), we get :M > V, V >S > N or M>V > S > N. Clearly, Nikunj is the youngest.

From II, we know that Copal's brother was born in 1982.

From III, we find that Gopal's brother was 8 years younger to him i.e. Gopal was born in 1974.

From I, we find that Sanjay is 6 years older than Gopal. Thus, Sanjay was born in 1968.

Observing I, II and III, we find that similar letters have similar code symbols at the corresponding places in the code. So, this is direct-coding.

Thus, to find the code for DATE, we need the code for D which can be obtained from I only (i.e. $.) and the codes for A, T and E which can be obtained either from II or III (@, # and % respectively).

From I, the order is : E, B, C or C, B, E.

From II, the order is : E, B.

From III, the order is : A, D, E.

Combining the above three, we get the order as : A, D, E, B, C. Clearly, E is sitting in the middle.

From II, we conclude that in a class of 40, Deepak ranks 23rd from the bottom i.e. 18th from the top.

From I and II, we find that Suman is 3 ranks below 18th rank from the top i.e. she ranks 21st from the top.

From II and III, we find that Suman is 3 ranks above 23rd rank from the bottom

i.e. she ranks 20th from the bottom or 21st from the top.

From the given statement, the descending order of heights is :__, Q,__, S,__.

From II, we have the order: _, Q, R, S,__. Thus, R is in the middle.

From III, we have the order : P, Q,__, S,__. But, according to I, T is not the shortest.

So, R is the shortest. Thus, we have the order : P, Q, T, S, R. So, T is in the middle.

From I and II, we conclude that Mathematics period began at 9.00 a.m., Biology period began at 8.00 a.m. and Physics period began at 11 a.m. So, the Chemistry period began at 10.00 a.m.

From I and III, we conclude that Mathematics period ended and Chemistry period began at 10.00 a.m.

From III, we have: Rajan's basic salary = Rs. 1550.

From I, we have: Vasu's basic salary = Rs. (1550 + 100) = Rs. 1650.

From II, we have: Rajan's other allowances = Rs. 2000 and Vasu's other allowances = Rs. 2050.

Therefore Vasu's monthly salary = Rs. (1650 + 2050) = Rs. 3700.

From I, we have: P > D, P > N, T > P i.e. T > P > D > N or T > P > N > D ...(i)

From II, we have: R > Q, T > R i.e. T > R > Q ...(ii)

From III, we have: T > Q, R > Q ...(iii)

Clearly, from (i) and (ii), we conclude that T is taller than each one of P, N, D, R and Q. So, T is the tallest.

To find the code for 'come', we need to have two statements which have one common code word and 'come' as the common word, which is there in I and III.