Answer: 49.85%
Step-by-step explanation:
Given : The physical plant at the main campus of a large state university recieves daily requests to replace florecent lightbulbs. The distribution of the number of daily requests is bell-shaped ( normal distribution ) and has a mean of 61 and a standard deviation of 9.
i.e.
and 
To find : The approximate percentage of lightbulb replacement requests numbering between 34 and 61.
i.e. The approximate percentage of lightbulb replacement requests numbering between 34 and
.
i.e. i.e. The approximate percentage of lightbulb replacement requests numbering between
and
. (1)
According to the 68-95-99.7 rule, about 99.7% of the population lies within 3 standard deviations from the mean.
i.e. about 49.85% of the population lies below 3 standard deviations from mean and 49.85% of the population lies above 3 standard deviations from mean.
i.e.,The approximate percentage of lightbulb replacement requests numbering between
and
= 49.85%
⇒ The approximate percentage of lightbulb replacement requests numbering between 34 and 61.= 49.85%
Answer:
No, the student is not correct. The correct expression is 9(n+13).
Step-by-step explanation:
"9 times the sum of a number and 13" means you must multiply 9 by the sum, not just by the number. 9n + 13 would be "the sum of 9 times a number and 13." Slightly different wording.
1. Change 1 7/8 to an improper fraction, which gives you 15/8.
2. Use KFC to divide fractions. KEEP the first term, FLIP the second and CHANGE to multiplication.
3. 15/8 x 4/3 = 60/24 = 2 1/2