Multiple choice

The sum of five numbers is 260. The average of the first two numbers is 30 and the average of the last two numbers is 70. What is the third number?

  1. 33

  2. 60

  3. 75

  4. Cannot be determined

  5. None of these
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B Correct answer
Explanation

Sum of 5 numbers = 260. Sum of first two = 2 * 30 = 60. Sum of last two = 2 * 70 = 140. Third number = 260 - (60 + 140) = 260 - 200 = 60.

AI explanation

The sum of the first two numbers is their average multiplied by two, giving 30 times 2, or 60. The sum of the last two numbers is 70 times 2, or 140. The total of these four numbers is 200, so the third number is the total sum of all five numbers minus this amount, yielding 260 minus 200, which equals 60.

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