In: Statistics and Probability
The following data comparing wait times at two rides at Disney are listed below:
| 
 Position  | 
 Pirates  | 
 Splash Mountain  | 
| 
 Sample Size  | 
 32  | 
 30  | 
| 
 Average Wait Time (In Minutes)  | 
 14.68  | 
 18.77  | 
| 
 Population Standard Deviation  | 
 11.87  | 
 16.79  | 
a)
Given CI level is 0.98, hence α = 1 - 0.98 = 0.05  
           
   
α/2 = 0.05/2 = 0.025, tc = t(α/2, df) = 2.33  
           
   
Pooled Variance
sp = sqrt(s1^2/n1 + s2^2/n2)
sp = sqrt(140.8969/32 + 281.9041/30)
sp = 3.7148
          
       
Margin of Error          
       
ME = zc * sp          
       
ME = 2.33 * 3.7148      
           
ME = 8.655          
       
          
       
CI = (x1bar - x2bar -zc * sp , x1bar - x2bar +zc * sp)  
           
   
CI = (14.68 - 18.77 - 2.33 * 3.7148 , 14.68 - 18.77 - 2.33 *
3.7148          
       
CI = (-12.7455 , 4.5655)  
b)
          
   
Below are the null and alternative Hypothesis,
Null Hypothesis, H0: μ1 = μ2
Alternative Hypothesis, Ha: μ1 ≠ μ2
Rejection Region
This is two tailed test, for α = 0.02
Critical value of z are -2.326 and 2.326.
Hence reject H0 if z < -2.326 or z > 2.326
Pooled Variance
sp = sqrt(s1^2/n1 + s2^2/n2)
sp = sqrt(140.8969/32 + 281.9041/30)
sp = 3.7148
Test statistic,
z = (x1bar - x2bar)/sp
z = (14.68 - 18.77)/3.7148
z = -1.10
P-value Approach
P-value = 0.2713
As P-value >= 0.02, fail to reject null hypothesis.