Question

Medal And Become Fan Rewarded for Correct Info/Answer Please Help Me :D

A company installs 5000 light bulbs, each with an average life of 500 hours, standard deviation of 100 hours, and distribution approximated by a normal curve. Find the percentage of bulbs that can be expected to last the period of time. Less than 690 hours.
A. 97.06%
B. 47.14%
C. 97.1%
D. 97.2%

Answer 1

first find z =(690-500)/100=1.9
now here we have to find the area under the normal curve for z=1.9

Answer 2

percenatge to last less than 690 hrs is C. 97.1%
and that between 500 and above but less than 690 is B. 47.14%

Answer 3

ty Matricked