Question

The mean of 5 observations is 15. If the mean of first three observations is 14 and that
of the last three is 17, find the third observation.
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Answer 1

Step-by-step explanation:

Given:-

The mean of 5 observations is 15. If the mean of first three observations is 14 and that of the last three is 17.

To find:-

Find the third observation.

Solution:-

The mean of 5 observations = 15

mean = sum of all observations / Number of all observations

=>Sum of all observations=mean×Number of all observations

=>Sum of all observations=15×5=75

Sum of all observations = 75

Mean of first three observations =14

Sum of first three observations =3×14=42

Mean of the last three observations = 17

Sum of all the last three observations = 3×17 =51

Sum of all first three and the last three observations = 42+51 = 93

In that third observation includes

Third observation = Sum of all 6 observations - Sum of all 5 observations

=>Third observation = 93-75 = 18

Third observation = 18

Answer:-

Third observation of the data = 18

Used formula :-

Mean = Sum of all observations / Number of all observations