The distribution of the number of occurrences of the letter t on the pages of a book is found to be a normal distribution with a mean of 44 and a standard deviation of 18. If there are 500 pages in the book, which sentence most closely summarizes the data?

A. The letter t occurs less than 26 times on approximately 170 of these pages.

B. The letter t occurs less than 26 times on approximately 15 of these pages.

C. The letter t occurs more than 26 times on approximately 420 of these pages.

D. The letter t occurs more than 26 times on approximately 80 of these pages.

.Answer:
mean = 44 
sd = 18 
that means that "26" is 1 s.d. down, or at the 16th %ile 

so, there is a .16 chance that "t" will occur less than 26 times on any single page. 
consequently, there is a .84 chance that it will occur more than 26 times on any single page. 

Using that information, and knowing that 16% of 500 is 80, and 84% of 500 is 420, can you see where "C" is correct?

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3 years ago

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What is lim x→-3 sqrt x^2-8

vitfil [10]

If the -8 is under the square root, then...

$\displaystyle L = \lim_{x\to -3} \sqrt{x^2-8}\\\\L = \sqrt{(-3)^2-8}\\\\L = \sqrt{9-8}\\\\L = \sqrt{1}\\\\L = 1\\\\$