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The mean of a set of 80 observations is 60. It was later discovered that three observations, 72, 68, and 70, were incorrectly recorded as 27, 32, and 35. What is the correct mean?

Option: 1

56.9


Option: 2

57.4


Option: 3

96.2


Option: 4

60.07


Answers (1)

best_answer

To find the correct mean, we need to adjust the three incorrectly recorded observations and recalculate the mean.

The sum of the original 80 observations is 60 \times 80 = 4800.

We need to subtract the incorrect values (27, 32, and 35) and add the correct values (72, 68, and 70) to the sum.

Corrected sum = (4800 - 27 - 32 - 35) + 72 + 68 + 70 = 4800 - 27 - 32 - 35 + 72 + 68 + 70 = 4806.

The correct mean is the corrected sum divided by the number of observations (80).

Corrected mean = 4806 / 80 = 60.075.

Therefore, the correct mean is approximately 60.075.

 

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