A study was done on the propagation of ultrasonic stress wave through a substance. In particular, attenuation (reduce in amplitude of stress wave measured in neper/cm) in fiber-glass-reinforced polyester composites was measured. The target attenuation is 2.3 neper/cm. Attenuation values are known to have the standard deviation of 0.25. Supposing that attenuation values follow a normal distribution with the mean = 2.3 and standard deviation = 0.25.
a. Determine the probability that attenuation is less than 2.5?
b. There is a 2.5% chance that attenuation is greater than ______