The breaking strength of plastic bottles is normally distrubuted with a variance

Question

The breaking strength of plastic bottles is normally distrubuted with a variance of 25. the process has a reject rate of 0.0197 for bottles that fall below the specification of 255 pounds per square inch (psi).on the basis of this information- the mean breaking strength is approx how many pounds psi ??

Please can someone help- it was answered before but the value of p=0.0197 was used to get another value of -0.2.06 and I am unsire of this-so please can you go through each step clearly.

Much appreciated

thank you

Explanation / Answer

P(X < 255) = 0.0197
Formula:z = (X - mean)/std. dev.
P(Z < (255 - mean)/sqrt(25)) = 0.0197

Using z table, for p-value = 0.0197, z = -2.06

Therefore, -2.06 = (255-mean)/sqrt(25), mean = 265.3

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

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