Question

Calculate the negative critical value for a t-interval when a =0.10 and n=41. Give 3 decimal places. Answer: Calculate the positive critical value associated with a confidence interval of a proportion (p) with C-level 98% Answer:

Answer 1

Solution :

Given, n = 41 , $\alpha$ = 0.10

$\alpha$ = 0.10

$\therefore$  $\alpha$/2 = 0.10 $\slash$ 2 = 0.05

Also, d.f = n - 1 = 41 - 1 = 40

$\therefore$  
ta/2.d.f-
  =  
ta/2.n-1
  =  $url=https://latex.codecogs.com/gif.latex?t&t=1596233733&ymreqid=69d777f6-ff7f-1f97-1c27-8e010301ba00&sig=ft_Q2525UIrjIgER3hFhxw--~D$_0.05,40 = 1.684

( use t table or t calculator to find this value..)

Solution :

construct 98% confidence interval.

$\therefore$ c = 0.98

$\therefore$$\alpha$ = 1- c = 1- 0.98 = 0.02

$\therefore$  $\alpha$/2 = 0.02 $\slash$ 2 = 0.01 and 1- $\alpha$ /2 = 0.99

Search the probability 0.99 in the Z table and see corresponding z value

$\therefore$$Z_{\alpha/2}$ = 2.326