a) If the mean of 7,9,11,13,15,17, and X is 13. Which the
number is X?
b) The mean of 9 consecutive odd numbers is 13. Write the
numbers?
Answers
If the average (arithmetic mean) of n consecutive odd integers is 10, : Data Sufficiency (DS)
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tonebeeze
Dec 9, 2010

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QUESTION STATS:
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64% (01:55) correct
36% (02:09) wrong
If the average (arithmetic mean) of n consecutive odd integers is 10, what is the least of the integers?
(1) The range of the n integers is 14
(2) The greatest of the n integers is 17
Spoiler: OA
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Most Helpful Expert Reply
Bunuel
EXPERT'S
POST
Dec 9, 2010
If the average (arithmetic mean) of n consecutive odd integers is 10, what is the least of the integers?
Odd consecutive integers is an evenly spaced set. For any evenly spaced set the mean equals to the average of the first and the last terms, so in our case  --> . Question: 
(1) The range of the n integers is 14 --> the range of a set is the difference between the largest and smallest elements of a set, so  --> solving for  --> . Sufficient.
(2) The greatest of the n integers is 17 -->  -->  --> . Sufficient.
Answer: D.