Solution:

The worth of that coin is zero. This is because the B.C. and A.D. dating system was not empowered till the year 525. So the coin is probably fake.

Solution:

1st Bag = One Coin
2nd Bag = Two Coins
3rd Bag = Four Coins
4th Bag = Eight Coins
5th Bag = Sixteen Coins
6th Bag = Thirty Two Coins
7th Bag = Sixty Four Coins
8th Bag = One Hundred and Twenty Eight Coins
9th Bag = Two Hundred and Fifty Six Coins
10th Bag = Remaining Coins.

Now imagine any amount in your mind and you will find out that you can give any amount by just using the pouches (without opening them)

Solution:

12

Explanation:
The amount won and lost by both is equal.
Thus 2x = 3(20-x) --- x in the number of times heads came
X = 12

Solution:

If all other conditions are fair, then the toss will generate a 52:48 distribution in the favor of heads. The toss boas factor will then be 52/48.

Using the same approach, if the coin will generate a 49:51 distribution in the favor of tails, the coin bias factor for heads will be 49/51.

Using the results, we can say that the combined bias factor is (52 * 49) / (51 * 48) = 2548 / 2448 which can be canceled if the floor bias factor is 2448 / 2548. The floor will generate a distribution factor of 2448 / (2558 + 2448) : 2548 + 2448) in favor of tails. If you calculate roughly, it will be 51.00080064% tails.

Solution:

20 paisa coins : 200
25 paisa coins : 124

Explanation:
Say he collect 20-paisa coins be A
Say he collect 25-paisa coins be B
=>number of 25-paisa coins = (324 - A).

Therefore,
0.20 X A + 0.25 (324 - A) = 71
=>20A + 25 (324 - A) = 7100
=>5A = 1000
=>A = 200.

Hence, number of 25-paisa coins = (324 - A) - 124.

Solution:

Simply push the cork into the bottle and shake the marble out.