Unit 1 Representing and Interpreting Data
10) Another important example not in the tutorial: The distribution of the number of occurrences of the letter ton
the pages of a book is found to be a normal distribution with a mean of 35 and a standard deviation of 6. If there
are 400 pages in the book, the letter (t) occurs more than 47 times in how many pages of the book?
1) Draw and label the normal distribution curve.
2) 47 is 2 standard deviation from the mean.
MORE THAN would be to the right of 47.
3) There are 2.35% and 15% of the data to the
right of 47, so 2.35 +.15 = 2.5.
4) Calculate 2.5% of 400. Turn 2.5 to a decimal
.025, multiply 400 and .025.400 (.025) - 10.
5) ANSWER: The letter (t) occurs more than 47
times on 10 pages of the book.
17 23
29
35
41
53
I