Question

the mean of 5 observations is 15 If mean of first three observation is 14 and that of the last is 17 find the third observation

Answer 1

Given that Mean of 5 observations is 15.  Therefore the sum of observations = 15 * 5 = 75.  Given that mean of the first 3 observations is 14.  Therefore the sum of first three observations = 14 * 3 = 42.  Given that mean of the last 3 observations is 17.  Therefore the sum of the last three observations = 17 * 3 = 51.   Hence,  The third observation = (42 + 51) - 75                                       = 93 - 75                                       = 18.   Hope this helps!