A) 9.56x10^38 ergs B) 7.4x10^-3 mm A). For the sun, just multiply the power by time, so 3.9x10^33 erg/sec * 2.45x10^5 sec = 9.56x10^38 B) Of the two values 7.4x10^-3 and 7.4x10^3, the value 7.4x10^-3 is far more reasonable as a measurement for blood cell. Reason becomes quite evident if you take the 7.4x10^3 value and convert to a non-scientific notation value. Since the exponent is positive, shift the decimal point to the right. So 7.4x10^3 mm = 7400 mm, or in easier to understand terms, over 7 meters. That is way too large for a blood cell when you consider that you need a microscope to see one. Now the 7.4x10^-3 mm value converts to 0.0074 mm which is quite small and would a reasonable size for a blood cell.
