Solution:

TIF56

Explanation:
The password is formed as:
T (5th letter of Shruti)
I (5th letter of Arshika)
F(1st letter of Friday)
5(5th day of week)
6(Length of Friday)

Similarly, we will pick the 1st letter for Monday and 3rd letter for Wednesday.

Solution:

1000$ - (Profit he earned in antique watch)

Solution:

Congratulations

Explanation:
Message Was: Company Piano Numb Dining Racial Mozetta Traitor Meou Legacy Quintana Trick Missi Orange Frozen Sapphire

Pick the 1st letter of the first word, 2nd letter of the second word, Pick 1st letter from the third word and so on.

Company - C
Piano - O
Numb - N
Dining - G
Racial - R
Mozetta - A
Traitor - T
Meou - U
Legacy - L
Quintana - A
Trick - T
Missi - I
Orange - O
Frozen - N
Sapphire - S

Solution:

They were playing tennis.

Tiger Phil
30 - 30
40 - 30 (Phil hit a bad shot)
Game won - 30 (Tiger hit an awesome shot)

Solution:

In Mansion M2, we know that older child is boy, therefore there are two cases
Older Younger
Boy Girl
Boy Boy
Probability of at least one girl child: 1/2 => 50%

In Mansion M1 there are three cases
Older Younger
Boy Girl
Boy Boy
Girl Boy
Probability of at least one girl child: 2/3 => 66.67%

Solution:

Wednesday

Explanation :
There is two way to interpret this.
A) If x + 1 ==> x - 1
Then
x ==> x - 2
x - 2 = Friday
x = Sunday

B)If x - 1 ==> x + 1
Then
x ==> x + 2
x + 2 = Friday
x = Wednesday

Option B) makes sense and hence the answer.

Solution:

Federer serves first

Explanation:
The one who serves first can serve 5 and other will serve four.

== Option A ==
If Federer serve 4 and Nadal serve 5
Then five service breaks and Federer winning 6:3 not possible.

== Option B ==
Federer serve 5 and Nadal serve 4
There are five service breaks and score is Federer 6 - Nadal 3
i.e
On Federer serve, Federer wins 3 and lost 2
On Nadal serve, Federer wins 3 and lost 1

Solution:

It can be solved as shown.

Solution:

Rashid's son-1: 1 11 21 31 41 51 61 71 81
Rashid's son-2: 2 12 22 32 42 52 62 72 73
Rashid's son-3: 3 13 23 33 43 53 63 64 74
Rashid's son-4: 4 14 24 34 44 54 55 65 75
Rashid's son-5: 5 15 25 35 45 46 56 66 76
Rashid's son-6: 6 16 26 36 37 47 57 67 77
Rashid's son-7: 7 17 27 28 38 48 58 58 78
Rashid's son-8: 8 18 19 29 39 49 59 69 79
Rashid's son-9: 9 10 20 30 40 50 60 70 80

Solution:

The code is 645
Explanation :
A) From Clues 1st and 2nd we know that one 9 is not in the code
B) From Clue 2nd we know that 9 3 and 8 are part of code
C) From Clue 3rd we know that 4 and 6 are part of code
D) From Clue 5th we know that 1 and 2 are not part of the code as we know 6 is part of the code and just 1 of 3 numbers is part of code.
E) From Clue 4th we know that 5 is also in the code as 8 and 1 are not part of code.

So the code is: 645