Learn About the Change in Penny Composition over Time

What is the difference between old and new pennies in terms of composition and mass?

Old pennies were made of copper and zinc with a mass of 3.1g. New pennies are made of copper-plated zinc and have a mass of 2.5g.

What is the percentage of the new penny's mass compared to the old penny's mass?

A new penny's mass is what percent of an old penny's mass?

Answer

The new penny's mass is 81% of the old penny's mass.

Pennies in the past were commonly made of a combination of copper and zinc, weighing about 3.1 grams each. However, due to the rising cost of copper and other factors, the composition of pennies changed over time. Modern pennies are now made of zinc with a thin layer of copper coating, weighing about 2.5 grams each.

When calculating the percentage difference in mass between the old and new pennies, we can use the formula for percentage change:

Percentage Change = [(New Value - Old Value) / Old Value] x 100%

Substitute the values of the new and old penny masses into the formula:

Percentage Change = [(2.5g - 3.1g) / 3.1g] x 100%

Percentage Change = [(-0.6g) / 3.1g] x 100%

Percentage Change = -0.1935 x 100% = -19.35%

Since the percentage change is negative, we need to find the absolute value to get the positive difference:

Absolute Value = |-19.35%| = 19.35%

Therefore, the new penny's mass is 19.35% less than the old penny's mass. In other words, the new penny's mass is equivalent to 81% of the old penny's mass.