Solution:

19

Explanation:
The Cost of 1st Wizard is: 50 i.e Total coins spend: 50
The Cost of 2nd Wizard is: 100 i.e Total coins spend: 150
The Cost of 3rd Wizard is: 150 i.e Total coins spend: 300
The Cost of 4th Wizard is: 200 i.e Total coins spend: 500
The Cost of 5th Wizard is: 250 i.e Total coins spend: 750
The Cost of 6th Wizard is: 300 i.e Total coins spend: 1050
The Cost of 7th Wizard is: 350 i.e Total coins spend: 1400
The Cost of 8th Wizard is: 400 i.e Total coins spend: 1800
The Cost of 9th Wizard is: 450 i.e Total coins spend: 2250
The Cost of 10th Wizard is: 500 i.e Total coins spend: 2750
The Cost of 11th Wizard is: 550 i.e Total coins spend: 3300
The Cost of 12th Wizard is: 600 i.e Total coins spend: 3900
The Cost of 13th Wizard is: 650 i.e Total coins spend: 4550
The Cost of 14th Wizard is: 700 i.e Total coins spend: 5250
The Cost of 15th Wizard is: 750 i.e Total coins spend: 6000
The Cost of 16th Wizard is: 800 i.e Total coins spend: 6800
The Cost of 17th Wizard is: 850 i.e Total coins spend: 7650
The Cost of 18th Wizard is: 900 i.e Total coins spend: 8550
The Cost of 19th Wizard is: 950 i.e Total coins spend: 9500
The cost of 20th Wizard is: 1000 i.e Total coins spend: 10500 .... more than 10,000.

Solution:

This is more of a philosophical question than being a riddle or a puzzle. The action of Brian directly led to the result which is the death of Chris. Thus he murdered Chris. In a sense, Chris died due to the lack of water. It is the circumstances that ultimately led to his death.

Solution:

Just One!

example
If u get Blue rock with label as "blue+red" => this is red as all labels are wrong.
In this way u can logically solve this puzzle.

Solution:

Rhea will open just one present.
Cindy|Y - Y is the 25th alphabet
Duk|E - E is the 5th alphabet
Joh|N - N is the fifteenth alphabet
Rhe|A - A is the first alphabet

Solution:

4 6 5 3 (from magician perspective)
3 5 6 4 (viewer perspective)

Detail:

From user perspective:
3 5 6 4 => 5 6 4 3 => 6 5 4 3

For magician perspective
3 4 5 6 (ascending order as)

Solution:

Since every bacterium divides into two in two minutes and we know the fact that the dish was half filled with bacteria at 3 pm, after exactly 2 minutes, all will divide into two and will fill the petri dish. Thus, the petri dish will become full at 3:02 pm.

Solution:

31

Explanation:
Ramanujan lighting the candles in binary.
11110 =30
11111 =31

Solution:

Selfie
Explanation:
: Selfie = is six letter word
: Self = The first four letter is me.
: e = The second and last letter are the same.
: fee = The fourth second and last letter are payment.

Solution:

She is near the trunk of the tree as shown below.

Solution:

They use the bricks and dirt from the tunnel to stand on it.

Solution:

10

Explanation:
Equation 1 + 9 + 11 = 1 can be derived from
One (o) + nine (n) + eleven (e) = one => 1

Similarly for equation,
12 + 11 + 9
Twelve (t) + eleven (e) + nine (n) => ten (10)