The mean of 100 observation is found to be 40. If at the time of compution two items were wrongly taken as 30 and 27 instead of 3 and 72. Find the correct mean

40.18

Step-by-step explanation:

According to this question, the mean of 100 observation is found to be 40. This means that the number of values in the set of data is 100. However, at the time of computation two items were wrongly taken as 30 and 27 instead of 3 and 72.

The mean is derived by dividing the sum of values in the data (Σx) by the number of observations (n) i.e.

Mean = Σx/n

For the computation error:

Mean = 40

Let x represent the sun of other 98 values except 30 and 27

n = 100

40 = x + 30 + 27/100

40 = 57 + x/100

Cross multiply

4000 = 57 + x

x = 4000 - 57

x = 3943.

Sum of other 98 values = 3943.

Now, let's find the correct mean with correct values of 3 and 72;

Mean = Σx/n

Mean = 3943 + 3 + 72/100

Mean = 4018/100

Mean = 40.18

the answer is 15% decrease