Answer:
The approximate percentage of lightbulb replacement requests numbering between 54 and 63 is of 49.85%.
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
Approximately 68% of the measures are within 1 standard deviation of the mean.
Approximately 95% of the measures are within 2 standard deviations of the mean.
Approximately 99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 54, standard deviation = 3.
What is the approximate percentage of lightbulb replacement requests numbering between 54 and 63?
63 = 54 + 3*3
So between the mean and 3 standard deviations above the mean.
The normal distribution is symmetric, which means that 50% of the values are below the mean and 50% are above.
Of those 50% above, 99.7% are below 63. So
0.5*0.997 = 0.4985
0.4985*100% = 49.85%
The approximate percentage of lightbulb replacement requests numbering between 54 and 63 is of 49.85%.
