Question

Mean of 15observations is 10then if one of the observation is taken 20 instead of 15.find correct mean

Answer 1

Mean of 15 observation = sum of 15 observation / 15

10 = sum of 15 observation / 15

Sum of 15 observation = 150

And now in sum we have to subtract 20 and add 15

So 150-20+15

Sum of 15 observation = 145

So new mean of observation = 145/15

= 9.6

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