The mean and SD of 63 children on an arithmetic test are respectively 27, 6 and 7.1. to them are added a new group of 26 who had less training and whose mean is 19.2 and SD. 6.2 The values of the combined group differ from the original as to (i) the mean and (ii) the SD is

The mean and SD of 63 children on an arithmetic test are respectively

1.	The mean and SD of 63 children on an arithmetic test are respectively 27, 6 and 7.1. to them are added a new group of 26 who had less training and whose mean is 19.2 and SD. 6.2 The values of the combined group differ from the original as to (i) the mean and (ii) the SD is
A.	25.1, 7.8
B.	2.3, 0.8
C.	1.5, 0.9
D.	None of these
Answer» B. 2.3, 0.8

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The mean and SD of 63 children on an arithmetic test are respectively 27, 6 and 7.1. to them are added a new group of 26 who had less training and whose mean is 19.2 and SD. 6.2 The values of the combined group differ from the original as to (i) the mean and (ii) the SD is

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