11. Five different numbers are chosen from the numbers 4, 7, 9, 11, 12, and 15.
They are then added together.
Which of the following statements is correct?
We analyze the sum of five numbers chosen from {4, 7, 9, 11, 12, 15}.
Step 1: Minimum and Maximum Sums
The smallest possible sum: 4 + 7 + 9 + 11 + 12 = 43
The largest possible sum: 7 + 9 + 11 + 12 + 15 = 54
Since 43 is the minimum sum and 54 is the maximum sum, the sum can be both below and above 45, meaning option (5) is incorrect.
Step 2: Checking Multiples of 5
The sum can be 43, 45, 47, 49, 51, 54, etc.
45 is a multiple of 5, meaning the sum is not always a multiple of 5, so option (1) is incorrect.
Step 3: Checking Even Totals
The sum of five numbers depends on how many evens and odds we choose.
The numbers 4, 12 are even, while 7, 9, 11, 15 are odd.
Since choosing five numbers always includes at least three odd numbers, the sum can be either odd or even, so option (2) is incorrect.
Step 4: Checking Multiples of 4
The sum can be 43, 45, 47, 49, 51, 54, etc.
Among these, 54 is a multiple of 4, meaning the sum can be a multiple of 4, so option (3) is correct.
Step 5: Checking Multiples of 3
The possible sums are 43, 45, 47, 49, 51, 54.
45, 51, and 54 are all multiples of 3, meaning the sum can be a multiple of 3, so option (4) is incorrect.