1. Assume that 95% of all specimen have a hardness less equal to +c. For what va

Question

1. Assume that 95% of all specimen have a hardness less equal to +c. For what value of c that satisfies this case?

Material science engineers determined that the Rockwell hardness of a particular alloy is normally distributed with mean 60 and standard deviation of 4. Assume that the acceptable hardness of this material is between 58 and 63. Alloys with a hardness that are outside this window are considered defective and are rejected. We would like to determine the probability that a random selected specimen of this type of alloy has an acceptable hardness. Use this information and answer question 8-18.

Explanation / Answer

1)for at 95% , z=1.64485

hence hardness=60+4*1.64485=66.5794 = +c

c=66.58-60=6.58

2)as std deviation =(X-mean)/zscore ; for here at 5%, z=-1.64485 and X=-5

hence std deviation =(-5-)/(-1.64485)=3.04

3)here for corresponding mean =(60-5)-(-1.64485)*4 =61.5794

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.