Let the amount of juice and water in original mixture '4x' litre and '3x' litre respectively.

According to given data,

4x/3x+6 =8/7

28x=24x+48

28x–24x=48

4x = 48

x = 12

Amount of juice = 4x = 4×12 = 48 litre.

Let marks obtained by N = x

M's marks = 0.80x

L's marks = 1.25 (0.80x)

K's marks = (0.90) (1.25) (0.80x)

= 0.9x

But 0.9x = 360 ⇒ x = 400

Percentage of Marks obtained by N

= 400 x 100/500 = 80%

Here the series follows the pattern that, product of succesive prime numbers i.e,

 2 × 3 = 6

 3 × 5 = 15

 5 × 7 = 35

 7 × 11 = 77

 11 × 13 = 143

 13 × 17 = 221

 17 × 19 = 323

So here in place of 77 the number 63 is written.

So the wrong number is 63.

Probability of occurrence of an event, 

P(E) = Number of favorable outcomes/Numeber of possible outcomes = n(E)/n(S)

⇒ Probability of getting head in one coin = ½, 

⇒ Probability of not getting head in one coin = 1- ½ = ½, 

Hence, 

All the 11 tosses are independent of each other.

∴ Required probability of getting only 2 times heads =122×129=1211

From statement I,

Time taken by Sriram to complete the work = 40 days

From statement II,

Time taken by Sriram to complete the wok = 30 days

So from both either by statement I or statement II we can find the time to complete the work.