A comparison of density values obtained by X-ray diffraction reveals that the percentages of vacant sites in aluminum (Al) are 0.0700% at 923 K and 0.0090% at 757 K.
Given this data, determine the number of vacant sites per cm3 at 550 K.
Express your answer as vacancies/cm3.
UPDATE: The grader on this problem has been corrected, and the number of attempts has been increased to 10.