Solution:

Letter 'E'

Solution:

49Th Day

Solution:

Trip round the world

Solution:

Megan (9:00AM) - Keira (11:00AM) - Penelope (8:00PM) - Charlize (10:00PM)

From the given data, it is clear that at least one female visited me in the morning and at least one female visited me in the evening. Also, from (4), Penelope did not visit me first. It means that Penelope visited me at 8:00 PM. From (3), Megan must have visited me at 9:00 AM. Also, either Charlize or Keira or both visited me in the morning. But from (2), only Keira must have visited me in the morning at 11:00 AM and hence, Charlize visited me at 10:00 PM.

Solution:

12

Solution:

48 minutes.

Donald duck's speed = X km/seconds
pool current speed = Y km/seconds

2/(X+Y) = 40
2/(X-Y) = 60

Solving the simultaneous equations gives X = 1/24

Therefore, to cover 2km will take 2/X = 48 seconds

Solution:

Scatter Brain

Solution:

nine games

Solution:

Submarine

Solution:

Forty.

The number of decks is irrelevant; the answer is the same if one or one-hundred decks are used.

Any card drawn will be a A,2,3,4,5,6,7,8,9,10,J,Q, or K, so there are 13 possibilities each time a card is drawn.

The fastest way to draw a four of a kind is if the first four cards all have the same 'value.' The slowest way, which provides the solution, is to first draw 13 three of a kinds, and then one more card.

Since 13 x 3 + 1 = 40, if 40 cards are drawn it is guaranteed that those forty cards contain at least one four of a kind.