Solution:

He should shoot at the ground.

If Kangwa shoots the ground, it is Rafael's turn. Rafael would rather shoot at Ferdinand than Kangwa, because he is better.
If Rafael kills Ferdinand, it is just Kangwa and Rafael left, giving Kangwa a fair chance of winning.
If Rafael does not kill Ferdinand, it is Ferdinand's turn. He would rather shoot at Rafael and will definitely kill him. Even though it is now Kangwa against Ferdinand, Kangwa has a better chance of winning than before.

Solution:

45 minutes

Explanation :
All you have to do is burn the first rope from both the ends and the second rope from one end only simultaneously. The first rope will burn in 30 minutes (half of an hour since we burned from both sides) while the other rope would have burnt half. At this moment, light the second rope from the other end as well. Where, the second rope would have taken half an hour more to burn completely, it will take just 15 minutes as we have lit it from the other end too.

Thus you have successfully calculated 30+15 = 45 minutes with the help of the two given ropes.

Solution:

101/125

Explanation:
This is an extremely tricky question. You have to find the probability where all of them have same number in mind. But if you try to do that, you will have to do a lot of calculations and utilize your brain plenty much. However, the trick to do this question is something opposite. We are not implying that you won’t get answer by directly calculating the probabilities, but it will take much time.

However, if you just go on calculating the negative probabilities, then you can simply subtract it from 1 to find the positive probability. Let us begin the operations and not confuse you further more.

Let us take two friends in the beginning. The probability that Adam and Bella don’t have the same number in their respective mind will be 4/5.

Now let us include Christopher in the scene. The probability that Christopher don’t have a digit same as either Adam or Bella will be 3/5.

Let us now include Drew as well. The probability that she does not have any number in mind which is same as either Adam or Bella or Christopher will be 2/5.

Now the combined probability that none of them has the same number in mind will be:
4/5 * 3/5 * 2/5 = 24/125

Now the probability that they have same number in mind will be:
1 – 24/125 = 101/125

Solution:

Step1 -> Start running both the hourglasses.
Step2 -> When 4 hours hourglass runs out, turn it over.
Step3 -> When 7 hours hourglass runs out, turn it over.
Step4 -> Again when 4 hours hourglass runs out, turn 7 minute hourglass over (it was running for exactly one minute.)
final step -> 8 minute already passed and allow one minute of 7 hour glass to get over. ==>9 minute

Solution:

None

The sum of numbers from 0-9(0,1,2,3,4,5,6,7,8,9) is 45 and therefore can be divisible by 3 and 9.

Solution:

12 steps:

Steps 11 Liter jug 6 Liter Jug
1. 11 -
2. 5 6
3. 5 0
4. 0 5
5. 11 5
6. 10 6
7. 10 0
8. 4 6
9. 4 0
10. 0 4
11. 11 4
12. 9 6 ==> i found 9 liter in 11liter jug(as required)

Solution:

Just 2

Day One: You make your first cut at the 1/7th mark and give that to the worker.
Day Two: You cut 2/7ths and pay that to the worker and receive the original 1/7th in change.
Day three: You give the worker the 1/7th you received as change on the previous day.
Day four: You give the worker 4/7ths and he returns his 1/7th cut and his 2/7th cut as change.
Day Five: You give the worker back the 1/7th cut of gold.
Day Six: You give the worker the 2/7th cut and receive the 1/7th cut back in change.
Day Seven: You pay the worker his final 1/7th.

Solution:

Steps:
1) Light fire on first bar from both the ends and second bar from one end.

2) After 30 seconds(when first bar gets completely burned out) , burn the second bar from second end as well.

3) When second run completely gets burned , you know its 45 seconds.

Solution:

If you ask the guard who always tells the truth, he would tell you the other guard would point you to the door of death. If you ask the guard who always lies, he would tell you the opposite door of the truth-telling guard and point you to the door of death. In either case, both guards will point to the door of death so you should choose the other one.

Solution:

20
Just count the nines in the numbers: 6, 16, 26, 36, 46, 56, 76, 86, 96, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69.
Note: 66 contains TWO nines