25. A radiograph made with an exposure of 12 mA per minute has a density of 0.8 in the area of interest. It is desired to increase the density to 2.0 in this area. By reference to a characteristic curve of the film, it is found that the difference in log e between a density of 0.8 and 2.0 is 0.76. The antilogarithm of log 0.76 is 5.8 (relative exposure factor). What must the new exposure time be to produce a radiograph with a density of 2.0, assuming the first exposure time was 1 minute?

25. A radiograph made with an exposure of 12 mA per minute has a density of 0.8 in the area of interest. It is desired to increase the density to 2.0 in this area. By reference to a characteristic curve of the film, it is found that the difference in log e between a density of 0.8 and 2.0 is 0.76. The antilogarithm of log 0.76 is 5.8 (relative exposure factor). What must the new exposure time be to produce a radiograph with a density of 2.0, assuming the first exposure time was 1 minute?