Math Riddles

Answer: The feathers. A pound of feathers is measured in avoirdupois weight, in which one pound equals 16 ounces. Precious metals are measured in troy weight, in which one pound equals 12 ounces.

However, the ounces are not measured in the same way. In avoirdupois weight, one ounce = 437.5 grains. In troy weight, one ounce = 480 grains.

So, one pound of feathers weighs (16)x(437.5 grains) = 7,000 grains. One pound of gold weighs (12)x(480 grains) = 5,760 grains.

Answer: When he gets on the subway it is 6 stops away from the end of the line (end of the track). So when it reaches this point it begins to work backwards. So when it goes back one stop he has traveled 7 stops but is only 5 away from where he began.

Answer: 0%. No matter which answer you choose you are incorrect. All of the answers create a logic loop.

Answer: He just doesn't take the bet. This gives him a 100 percent chance of getting the money home. If he takes the bet with 1 die he has a 50 percent chance of winning. If he takes the bet with 2 dice he has about a 56 percent chance of winning. If he takes the bet with 3 dice he has about a 42 percent chance of winning.

Answer: The numbers are 3 and 4.

Since Sam knows the sum of the numbers (x + y) he would only know the answer immediately if the sum was 4 (2 + 2) or 5 (3 + 2). Then when Pete (who knows x*y) knew that Sam didn't know the answer the product must have several numbers that add up to the sum (7 = 3 + 4, 7 = 5 + 2). When Pete doesn't know the answer at this point we know the product must have more than one pair of viable factors (12 = 3 * 4, 12 = 6 * 2). At this point Sam knows the numbers are 3 and 4 because they are the only numbers that meet these criteria.