A company installs 5000 light bulbs, each with an average life of 500 hours, standard deviation of 100 hours, anddistribution approximated by a normal curve. Find the approximate number of bulbs that can be expected to last thespecified period of time.
-Between 500 hours and 675 hours
A) 4700
B) 2256
C) 2300
D) 4800

Question

Quizplus · Accepted Answer

To find the number of bulbs lasting between 500 and 675 hours, we calculate the z-scores for 500 and 675 hours. The z-score for 500 hours is 0 (since it's the mean), and for 675 hours, it's (675-500)/100 = 1.75. Using the standard normal distribution table, the area between z = 0 and z = 1.75 is approximately 0.4599. Therefore, the number of bulbs is 0.4599 * 5000 ≈ 2300.

A Company Installs 5000 Light Bulbs, Each with an Average