View the step-by-step solution to:


The life time of a certain kind of batteries has a mean life of 400 hours and standard deviation as 45 hours.

Assuming the distribution of life time to be normal, find (i) the percentage of batteries with a life time of at least 470 hours (ii) the proportion of batteries with life time between 385 and 415 hours. (iii) the minimum life of the best 5% of batteries

Recently Asked Questions

Why Join Course Hero?

Course Hero has all the homework and study help you need to succeed! We’ve got course-specific notes, study guides, and practice tests along with expert tutors.


Educational Resources
  • -

    Study Documents

    Find the best study resources around, tagged to your specific courses. Share your own to gain free Course Hero access.

    Browse Documents
  • -

    Question & Answers

    Get one-on-one homework help from our expert tutors—available online 24/7. Ask your own questions or browse existing Q&A threads. Satisfaction guaranteed!

    Ask a Question