nicole de la torre 12615 742 P Quiz 73 Overview This Questio

nicole de la torre 12/6/15 7:42 P Quiz 7.3 Overview This Question: Time Limit: 0:00:00 3 of 6 compiete 1 pt This Test: 6 pts Do one of the following, as appropriate. (a) Find the critical value Za/ (b) find the crtical value ta, 2z (c) state that neither the normal nor thet distribution applies. Confidence level 90%; n-16; is known; population appears to be very skewed Do one of the following, as appropriate. (a) Find the critical value za (b) Click here to view a table of critical t-values. Click her lo view page of the stanrd nomal mable. Find the critical value. OA, Za/2= 1.645 OB. t/2-1.341 OD. ta/2- 1.753 OE. Neither normal nor t distribution applies. Click to select your answer

Solution

1.

As the population is very skewed, and sample size is small (<30), then, we use t distribution.

Thus, for c = 0.90, then

alpha = (1-c)/2 = (1-0.90)/2 = 0.05

Thus, as df = n - 1 = 16 - 1 = 15, then by table/technology,

t(alpha/2) = 1.753 [ANSWER, D]

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2.

A)

Best point estimate = xbar = 151.81 [ANSWER]

b)

Note that              
Margin of Error E = z(alpha/2) * s / sqrt(n)              
Lower Bound = X - z(alpha/2) * s / sqrt(n)              
Upper Bound = X + z(alpha/2) * s / sqrt(n)              
              
where              
alpha/2 = (1 - confidence level)/2 =    0.005          
X = sample mean =    151.81          
z(alpha/2) = critical z for the confidence interval =    2.575829304          
s = sample standard deviation =    30.61          
n = sample size =    40          
              
Thus,              
Margin of Error E =    12.46666856          
Lower bound =    139.3433314          
Upper bound =    164.2766686          
              
Thus, the confidence interval is              
              
(   139.3433314   ,   164.2766686   ) [ANSWER]

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