View the step-by-step solution to:


Two makes of electric bulbs A and B are tested and observed. Bulbs of make A exhibit mean life of 900 hrs. and

standard deviation of 30 hrs. Those of make B show mean life of 860 hrs. and standard deviation of 20 hrs. Find the probability that the mean life based on a random sample of 40 bulbs of make A being, say, 28 hours less than the mean life of bulbs of make B based on a random sample of 30 bulbs

Top Answer

View the full answer
picture 1.png

Sign up to view the full answer

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
Ask a homework question - tutors are online