Question

Suppose a sheet of 100 stamps is 0.62 millimeters thick. If a stack of sheets contains 10,000,000 stamps, how many millimeters thick is the stack? Write the answer in scientific notation.

Answer 1

62,000 millimeters, because 10,000,000/ 100 is 100,000. 100,000 x .62 is 62,000.

Answer 2

You can set up a proportion for this. Let x be the thickness obtained by stacking 10 million stamps

100:0.62 : : 10,000,000 : x

Now set it up as a proportion so you can cross multiply.

100/0.62 = 10,000,000/x Cross multiply

100x = 0.62 * 10,000,000 change 0.62 to a fraction

0.62 = 62 / 100 Substitute 62/100 into the proportion

100 x = 62/100 * 10,000,000 Divide by 100

100 x = 62 * 100, 000 Multiply by 61

100x = 6,200,000 Divide by 100 on both sides

x = 6,200,000/100 62,000 mm

x = 62,000 mm

x = 6.2 * 10^4 mm answer