Average of all integers in a range that are divisible by k

The same question, asked 4 times: 12 Sep 2025 S1*, 12 Sep 2025 S3*, 14 Sep 2025 S3*, 15 Sep 2025 S2. Every wording below, oldest first.

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Question 1
12 Sep 2025 S1
57 $What is the average of all integers between 100 and 250 that are exactly divisible by 11?$
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Question 2
12 Sep 2025 S3
60 $What is the average of all integers between 300 and 450 that are exactly divisible by 13?$
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Question 3
14 Sep 2025 S3
56 $What is the average of all three-digit numbers divisible by 23?$
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Question 4
15 Sep 2025 S2
55 $What is the average of all numbers between 1000 and 1300 that are divisible by 25?$
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Question 1