Final answer:
None of the provided efficiency options (50-60%, 60-70%, 70-80%, 80-90%) match the typical efficiency of a blue fiberglass air filter, which is generally rated at less than 20% according to MERV ratings.
Step-by-step explanation:
The approximate efficiency of the throwaway blue fiberglass air filter is not one of the values provided in the options, such as 50-60%, 60-70%, 70-80%, or 80-90%. To calculate percentage efficiency for any device, including air filters, the general formula used is percentage efficiency = (useful energy output / total energy input) × 100%.
Typically, standard throwaway fiberglass air filters have a lower efficiency in filtering out small particles compared to more advanced filter types.
They are often rated within the range of less than 20% efficient at capturing particles 1 to 3 microns in size according to the Minimum Efficiency Reporting Value (MERV) ratings. Hence, none of the provided options are correct for a standard throwaway blue fiberglass air filter.