Question

Difficulty: EasyConsecutive Integers and Number Sets

If the sum of a set of 77 consecutive odd integers is 105105, what is the median integer of the set?

Answer: 15

Answer

The median integer of the set is 15.
For any set of evenly spaced numbers, such as consecutive odd integers, the arithmetic mean is equal to the median. Since the sum of the 77 integers is 105105, the mean is 105÷7=15105 \div 7 = 15. Therefore, the median of the set is 1515.

Step-by-Step Solution

1
Apply the property of evenly spaced sets.
For consecutive odd integers, the mean of the set is equal to its median.
The numbers in an arithmetic sequence are symmetrically distributed around the middle value.
2
Calculate the arithmetic mean.
Mean = SumNumber of terms=1057=15\frac{\text{Sum}}{\text{Number of terms}} = \frac{105}{7} = 15.
Dividing the sum of the terms by the count gives the average value.
3
Determine the median.
Median = 1515.
Because mean equals median for evenly spaced sets, the median must be 15.

Key Concept

Average and Median Equivalence in Evenly Spaced Sets
Estimated Time:45s
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