Average value of 20 observations 75. It
was known later that 97 had been read as
57. Accordingly, what was the correct
average value?
Answers
Answer:
27
Step-by-step explanation:
When we talk about the “mean” or the “arithmetic mean” of two or more quantities, we are actually talking about the average of those quantities.
The average of two or more quantities is found by simply adding the quantities together and then dividing this sum by the number of quantities. In this case, we have the following mean or average:
mean (average) = (The sum S of the observations)/(the number n of observations)
mean = S/n
28 = S/10
28(10) = 10(S/10)
280 = S
Since equality is symmetric, i.e., if a = b, then b = a, then we have:
S = 280
Since it was later discovered that one of the observations which was actually 14 was mistakenly read as 24, then the Sum S is 10 (24 – 14) too much; therefore, the correct mean is found as follows:
Correct mean = (S – 10)/n
= (280 – 10)/10
= 270/10
Correct mean = 27
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