Q. Find the average of all prime numbers between 20 and 40.
Answer: 30
Notes: There are four prime numbers between 20 and 40 and they are 23, 29, 31, 37. So now we have to find the average of these four numbers : = $latex \frac{23 + 29 + 31 + 37}{4}= 30.&s=1$ Option (D) is the correct answer

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