Multiple choice

If the mean of the following observations is 70, then what is the value of a? 68, 70, 72, a, 74, 76

  1. 60

  2. 62

  3. 64

  4. 66

  5. Na
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A Correct answer
Explanation

Mean = (68 + 70 + 72 + a + 74 + 76) / 6 = 70. Sum = 360 + a = 420. a = 60.

AI explanation

The mean formula states that the sum of the observations divided by the number of observations gives the mean. The sum of the 6 observations is 68 plus 70 plus 72 plus a plus 74 plus 76, which simplifies to 360 plus a. Since the mean is 70, the total sum must be 6 multiplied by 70, equaling 420. Solving 360 plus a equals 420 gives the value of a as 60.

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