The probability density of finding a particle somewhere along the x-axis is 0 for x < 1 mm. At x = 1 mm, the probability density is c. For x ≥ 1 mm, the probability density decreases by a factor of 8 each time the distance from the origin is doubled. What is the probability that the particle will be found in the interval 2 mm ≤ x ≤ 4 mm?