Medium Puzzles 

Workings

Hint
The first letter can only be B.

Answer
A badger.

Reasoning
My first is in bridge, but not in ridge = B

My second is in awake, and in mistake = A K E

My third is in danger, but not in ranger = D

My fourth is in strange, and in orange = R A N G E

My fifth is in spline, and in nine = I N E

My last is in river, and in diver = R I V E

Workings

Hint
Does the number of adults and children matter?

Answer
3,672.

Reasoning
The actual number of adults and children doesn't actually matter.

If all of the people were adults, then half of them (306) would be given 12 sweets:

  306 x 12 = 3672

If all of the people were children, then three quarters of them (459) would be given 8 sweets:

  459 x  8 = 3672

If there were 512 adults (so 256 would get 12 sweets = 3072) and 100 children (so 75 would get 8 sweets = 600):

  256 x 12 + 75 x 8 = 3672

We can change the numbers of adults and children, but it doesn't change the answer.

The reason for this lies in the fact that ¹/₂ adults x 12 sweets = ³/₄ children x 8 sweets (both are 6).

Workings

Hint
The first letters of the words are: W, W, S, Y, B, B, S, L, S, F.

Answers
  drift[wood]wind    home[work]bench    foot[step]mother   court[yard]stick    moth[ball]room quarter[back]ground   space[ship]yard    wild[life]span    your[self]less    back[fire]fighter

Workings

Hint
How many large pipes are required to drain the reservoir in 24 hours?

Answer
21 hours and 36 minutes.

Reasoning
Looking at the first clue:
   in 12 hours, 6 large pipes can drain 1 reservoir
   in 24 hours, 6 large pipes can drain 2 reservoirs
   (*) in 24 hours, 3 large pipes can drain 1 reservoir

Looking at the second clue:
   in 8 hours, 3 large + 9 small pipes can drain 1 reservoir
   in 24 hours, 3 large + 9 small pipes can drain 3 reservoirs

But, by (*), we know that in those 24 hours, 3 large pipes can drain 1 of those reservoirs.

Therefore, the other 2 reservoirs can be drained by the small pipes on their own:
   in 24 hours, 9 small pipes can drain 2 reservoirs
   in 24 hours, 1 small pipe can drain ²/₉ reservoirs
multiply the hours by 9:
   in 216 hours, 1 small pipe can drain 2 reservoirs
   in 216 hours, 5 small pipes can drain 10 reservoirs
divide the hours by 10:
   in 21.6 hours, 5 small pipes can drain 1 reservoir

21.6 hours = 21 hours and 36 minutes.