Solution:

17

Explanation:
1
3 = one (3 letters)
8 = three (5 letters) + one (3 letters)
13 = Eight (5 letters) + three (5 letters) + one (3 letters)
21 = Thirteen (8 letters) + Eight (5 letters) + three (5 letters) + one (3 letters)
17 = twentyOne (9 letters) + Thirteen(8 letters)

Solution:

288/61 hours (4 hours, 43 minutes and 17 seconds approx)

Explanation:
In 1 hour, the ratio of swimming pool filled by pipes:
1st pipe: 1/48
2nd pipe: 1/72
3rd pipe: 1/96
4th pipe: 1/6

All togther
1/48 + 1/72 + 1/96 + 1/6
=> (6+4+3+48) / 288 = 61/288.
=> 288/61 hours,

which is 4 hours 43 minutes and about 17 seconds.

Solution:

Oscaru and Austin.

Explanation:
The Chemist hide the name using periodic table as shown in below picture
76-20-44 => Os(76) + Ca(20) + Ru(44)
79-16-22-7=> Au(79) + S(16) + Ti(22) + N(7)

Solution:

When blind man "Grandpa" opened his bandages, the train must be passing through the dark tunnel. The man thought he was still blind and hence commit suicide.

Solution:

RS

Explanation:
The list is formed by using last two letter of planet's names in the order from Neptune To Mercury

NEPTU-NE
URAN-US
SATU-RN
JUPIT-ER
MA-RS
EAR-TH
VEN-US
MERCU-RY

Solution:

A Party

Solution:

SHERLOCK

Explanation:
The Number just denotes the position of the letter in the word.
6 Goals Marcos => S
3 Goals Cahil => H
2 Goals Cesar => E
5 Goals Hazard => R
3 Goals Willian => L
8 Goals Jorginho => O
1 Goal Charley => C
4 Goals Barkley => K

Solution:

A - Gold
D - Silver
C - Bronze

Solution:

He is on top of two rocks. Snipper's gun head can be shown.

Solution:

24 strikes - One Striker every hour

156 Strikes - Strike depends on the number of hours
(3rd hour - 3 strikes, 11th hour - 11 strikes)
Total Strikes = 2(1+2+3+4+5+6+7+8+9+10+11+12) = 156.

180 Strikes - 156 from previous + 24 (one strike every hour)

228 Strikes - 156 Strikes(Strike depends on the number of hours) + 72(24*3, one every quarter except for the 0th hour)
= 156 + 72 = 228

Hence all clocks are working fine.
24 strikes - One Striker every hour

156 Strikes - Strike depends on the number of hours
(3rd hour - 3 strikes, 11th hour - 11 strikes)
Total Strikes = 2(1+2+3+4+5+6+7+8+9+10+11+12) = 156.

180 Strikes - 156 from previous + 24 (one strike every hour)

228 Strikes - 156 Strikes(Strike depends on the number of hours) + 72(24*3, one every quarter except for the 0th hour)
= 156 + 72 = 228

Hence all clocks are working fine.