In how many days will Y alone complete the work?
I. X and Y together can complete the wok in 8 days.
II. Y and Z together can complete the work in 10 days.
III. X and Z together can complete the work in 12 days.

From Statement I and III,
Let marks in English be x
Marks in Science = x + 12
and marks in Mathematics = x + 32
From Statement II,
E + S + M = 197
x + x + 12 + x + 32 = 197
? 3x + 44 = 197
? 3x = 197 - 44 = 153
? x = 51
? Marks in English = 51

From Statement I,
SI = PRT/100
? P = (P x R x 10)/100
? R = 10%


From Statement II,
Difference (D) = PR²/(100)²
? 150 = (15000 x R²)/10000
? R = 10%

Thus, either Statement I or II is sufficient.

(A + B)'s 1 day's work = 1/8 ..........(i)
(B + C)'s 1 day's work = 1/10 ..........(ii)
(C + A)'s 1 day's work = 1/12 ............(iii)
Add the equation (i), (ii), (iii)
2(A + B + c)'s 1 day's work = 1/8 + 1/10 + 1/12
(A + B + C)'s 1 day's work = 1/2[1/8 + 1/10 + 1/12] ..........(iv)
Subtracting Eq. (iii) from Eq. (iv), we get B's 1 day's work.
then, required number of days = 1/(B's 1 day's work) .
So we need all above 3 statements to solve the given question.

Form Statement I,
R A      G E
Clearly , the left place or empty place is filled by N .
From Statement II ,
   A  N  G    
   G   N  A    
Clearly N is at third place ,
Hence, the data in Statement I alone or in Statement II alone are sufficient to answer the question .

From Statement I,
N > M > K
From Statement II ,
L > N
From both the Statement
L > N > M > K
but height of J is not clear .
Thus second tallest friend cannot be determined.
Hence, data neither in Statement I nor in Statement II are sufficient to answer the question .

Data are not sufficient even from Statement I and II both.

From Statement I,
R = (SI x 100) / (P x T)
? (1736 x 100)/(6200 x 2) = 14%

From Statement II,
1348.2 4500(1 + r/100)² - 4500
? 1348.2 + 4500 = 4500(1 + r/100)²
? 5848.2 = 4500((1 + r/100)²
? 5848.2/4500 = (1 + r/100)²
? 3249/2500 = (1 + r/100)²
? (57/50)² = (1 + r/100)²
? 1 + r/100 = 57/50
? r/100 = 57/50 - 1 = 7/50
? r = 7 x 100/50
? r = 14%

Both statement are alone sufficient.

Data given in Statement I alone are sufficient to answer the question

We know that,
Speed of boat in still water
= (Speed upstream + Speed downstream)/2
From Statements I and II,
Speed = (6 + 4)/2 = 10/2 = 5 km/h
So, answer can be determined from both statements.

From Statement II,
The ratio of their ages after 5 yr is 7 : 6
So, (6k + 5) / (5k + 5) = 7/6
? 36k + 30 = 35k + 35
? 36k - 35k = 35 - 30
? k = 5
? Age of anand = 6 x 5 = 30 yr
So, Statement II is alone sufficient.