Fill in the blanks such that the mean of the collection is 6.5: 3, 11, ___, ___, 15, 6. How many possibilities exist if only counting numbers are allowed?
Given: 6 values with mean 6.5
Formula: Sum = Mean × Number of values
Calculation: Total sum = = 39 Sum of known values = 3 + 11 + 15 + 6 = 35 Sum of two missing values = 39 - 35 = 4 Counting number pairs that sum to 4: (1, 3), (2, 2), (3, 1)
Answer: There are 3 possibilities.
Explanation
The chapter demonstrates finding unknown values when the mean is known. Use the formula: Sum = Mean × Number of values, then find what the missing values must sum to.
Solution Steps
Step 1: Calculate required total sum: Mean × n = = 39
Step 2: Sum of known values: 3 + 11 + 15 + 6 = 35
Step 3: Sum of two missing values: 39 - 35 = 4
Step 4: Find counting number pairs that sum to 4: (1, 3), (2, 2), (3, 1)
Step 5: Total possibilities = 3