Final answer:
A blood cell's diameter is actually about 8 micrometers (μm), which is 8 × 10^-6 meters in scientific notation or 8/1,000,000 meters as a fraction.
Step-by-step explanation:
The statement that a blood cell has a diameter of about 5 inches must be a typo because actual human red blood cells have a diameter of about 8 micrometers (μm). To express this diameter using a positive exponent and as a fraction, we use scientific notation. The diameter of a red blood cell can be written as 8 × 10-6 meters (since 1 μm = 1 × 10-6 meters) or approximately 8/1,000,000 meters as a fraction. Therefore, a correct estimation of a red blood cell diameter in positive exponent form is 8 × 10-6 meters and as a fraction is 8/1,000,000 meters.