A) 25.1, 7.8
B) 2.3, 0.8
C) 1.5, 0.9
D) None of these
Correct Answer: A
Solution :
[a] Mean and SD \[\sigma \] of the combined group are \[m=\frac{63\times 27.6+26\times 19.2}{63+26}=25.1\] Thus, AM is decreased by \[27.6-25.1=2.5.\] \[{{\sigma }^{2}}=\frac{63\times {{(7.1)}^{2}}+26\times {{(6.2)}^{2}}}{89}\] \[+\frac{63{{(25.1-27.6)}^{2}}+26{{(25.1-19.2)}^{2}}}{89}\] \[\Rightarrow \sigma =7.8\] (approx.)
You need to login to perform this action.
You will be redirected in
3 sec
