An industrial engineer is analyzing the structural strength of a concrete aggregate. Structural strength is normally distributed with o? = 1000 (psi)². What sample size is required if it is desired to...

Extracted text: An industrial engineer is analyzing the structural strength of a concrete aggregate. Structural strength is normally distributed with o? = 1000 (psi)². What sample size is required if it is desired to estimate the structural strength with an error that is less than 10 psi at 95% confidence? level Would the sample size increase or decrease if the confidence level becomes 90%? Include your solutions. O a. NONE O b. Sample size required at 95% confidence level is 154 Oc. Sample size required at 95% confidence level is 39. Reducing the confidence level to 90% decreases the required samples size O d. Sample size required at 95% confidence level is 39. Reducing the confidence level to 90% will increase the samples size for the error to be less than 10 psi