The mean of 20 observations is 12.5. By error, one observation was noted as (-15) instead of 15. Then the correct mean is ___?

The correct mean is -12.5.

Step by step explanation:

If one of the 20 observations is a negative number, then the mean would be negative. This is because, when a negative number is in contact with (meaning added, subtracted, multiplied by) a positive number, the whole answer is negative, because it's opposite signs.

Hope this helps! :D

20

step-by-step explanation:

step-by-step explanation:

given that there are two triangles j'k'l' and jkl>

the former is got by dilating the second one.

when drawn on a grid, (graph paper) coordinates of vertices of first triangle is

(6,12)j, (9,6)k and (12,9)l

side jk has length = distance between j and k

=

side j'k'=distance between j' and k'

=

ie j'k'l' has sides 1/3 of that of corresponding sides of jkl.

hence scale factor of 1/3 is used to get j'k'l'from jkl