Old coins will have more wear than new coins and so they will weigh less. As a matter of interest if you have two identical weight untarnished coins. You then tarnish one of the coins it will become heavier and will weigh MORE than the untarnished coin.
What is the minimum number of weighing needed to find the fake coin?
The above solution shows that 1 weighing is sufficient to detect a lighter fake among 3 coins.
Can banks weigh coins?
The amount of coins in a roll will vary depending on the denomination and which currency you’re using. However, by way of example, you can expect to find 50 U.S. pennies )1c) in a roll, 40 nickels (5c) in a roll, 50 dimes (10c) in a roll and 40 quarters (25c) in a roll. The bank will weigh the coins.
How to solve the problem of weighing coins?
So, the two problems can be solved in 3 steps. Divide the set of 90 coins into 3 sets of 30 coins each. Weigh two groups of 30 coins against each other. If equal, divide the rest 30 into 3 groups of 10 each. Weigh two groups here to reduce the problem either to claim1 or claim2.
Can you make a coin weigh the same?
The problem is, we’re only allowed the use of a marker (to make notes on the coins) and three uses of a balance scale. Here are the detailed conditions: 1) All 12 coins look identical. 2) Eleven of the coins weigh exactly the same. The twelfth is very slightly heavier or lighter.
How many coins in two weighings is the balance puzzle?
The problem has a simpler variant with three coins in two weighings, and a more complex variant with 39 coins in four weighings. This problem has more than one solution.
How can you tell the weight of a twelfth coin?
The twelfth is very slightly heavier or lighter. 3) The only available weighing method is the balance scale. It can only tell you if both sides are equal, or if one side is heavier than the other. 4) You may use the scale no more than three times. 5) You may write things on the coins with your marker, and this will not change their weight.
