Question

the mean of 11 observations is found to be 35. each observations is then changed to 15 less than 4 times the original observations. what is the mean of new observations
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Answer 1

Answer:

Let the terms be = x1, x2, x3.... x11

Then,

Mean = Sum of all observations/ Number of observations

=》 35 = (x1 + x2 ... + x11)/ 11

=》 x1 + x2 ... + x11 = 385 ...(1)

Now, according to the question :

x1' = 4x1 - 15

New mean = (4x1 - 15 + 4x2 - 15 ... + 4x11 - 15)/ 11

=》 New mean = (4(x1 + x2 ... + x11) - 11(15))/ 11

From (1):

=》 New mean = 4(385) - 11(15)/ 11

=》 New Mean = 125