Solution:

1611

Explanation:
The number on the right side is formed as (sum of digits of the 1st number)(number1/number2)
example,
24 $ 6 = 64 (2+4 = 6) (24/6 = 4)
35 $ 5 = 87 (3+5=8) (35/5 = 7)
63 $ 7 = 99 (6+3 =9) (63/7 =9)

Simillarly,
88 $ 8 = (8+8 = 16) (88/8 = 11)

Solution:

Daughter.

Solution:

There are 3 fruits (1 grapes, 1 apples, and 1 oranges).

Solution:

Move the coins as given in the figure and you will get the required result.

Solution:

Anybody will prefer the shop in the eastern market for sure. There are two reasons for it:
Firstly, since there are only two barbers in the town, the one running the shop in eastern market must have gotten his hair done by the one running the shop in the northern market and vice versa. Thus, if the barber in the eastern market has a shabby haircut, it must be due to the incompatibility.
Secondly, the neat and clean shop can be due to the scarcity of customers as well. While the untidy place refers to the fact that so many customers get their hair done in that shop.

Thus any one will opt for the barber shop in the eastern market.

Solution:

The two numbers are 4 and 13 whose product is 52 and sum is 17.

Solution:

60 minutes

Explanation:
Roy will be able to consume all the five tablets in an hour.

Tablet 1 will be taken in 0 min.
Tablet 2 will be taken in 15 min.
Tablet 3 will be taken in 30 min.
Tablet 4 will be taken in 45 min.
Tablet 5 will be taken in 60 min.

Solution:

The brain teaser can be solved as shown in the image below.

Solution:

It can be done in 8 moves as shown in the animated image below.

Solution:

To do it, the marbles must be arranged as the vertices of an octahedron. If you are unsure, check the image below.

Solution:

17 mins

The initial solution most people will think of is to use the fastest person as an usher to guide everyone across. How long would that take? 10 + 1 + 7 + 1 + 2 = 21 mins. Is that it? No. That would make this question too simple even as a warm up question.

Let’s brainstorm a little further. To reduce the amount of time, we should find a way for 10 and 7 to go together. If they cross together, then we need one of them to come back to get the others. That would not be ideal. How do we get around that? Maybe we can have 1 waiting on the other side to bring the torch back. Ahaa, we are getting closer. The fastest way to get 1 across and be back is to use 2 to usher 1 across. So let’s put all this together.

1 and 2 go cross
2 comes back
7 and 10 go across
1 comes back
1 and 2 go across (done)

Total time = 2 + 2 + 10 + 1 + 2 = 17 mins