Question

A test of a strac eason ng s given to a random sam le o students before and after hey completed a orma lo ic course. The results are given elo . o struct a 95 % confidence inte a e and erence between e re andat ers res Before 74 83 75 88 84 63 93 84 91 77 After 73 77 70 77 74 67 95 83 84 75 OA. 1.0 <6.4 O B. 02<Hd7.2 OD. 1.2 < μ-8.7

Answer 1

Solution:- (B) $0.2< \mu _{d}< 7.2$

$s = \sqrt{\frac{\sum (d-\bar{d})^{2}}{n-1}}$

s = 4.9453

95% confidence interval for the mean difference between the before and after scores is 0.2 < $\mu _{d}$ < 7.2.

$C.I = \bar{d}\pm t_{\alpha /2}\ast \frac{\sigma }{\sqrt{n}}$

C.I = 3.7 + 2.263*1.56383

C.I = 3.7 + 3.5389

C.I = ( 0.161, 7.239)

C.I = (0.2, 7.2)