The stiffness of a certain type of steel beam used in building construction has mean 30 kN/mm and standard deviation 2 kN/mm.

a. Is it possible to compute the probability that the stiffness of a randomly chosen beam is greater than 32 kN/mm? If so, compute the probability. If not, explain why not.

b. In a sample of 100 beams, is it possible to compute the probability that the sample mean stiffness of the beams is greater than 30.2 kN/mm? If so, compute the probability. If not, explain why not.

Answer:

Step 1 of 3:

Given the stiffness of a certain type of steel beam used in building construction has mean 30 kN/mm and standard deviation 2 kN/mm .

Step 2 of 3:

a). It is not possible to compute the probability the stiffness of a randomly chosen beam is greater than 32 kN/mm. Because we don't have any distribution to compute this probability, but only mean and standard deviation.