The reading speed of second grade students in a large city i

Solution

a)

We first get the z score for the critical value. As z = (x - u) sqrt(n) / s, then as          
          
x = critical value =    96      
u = mean =    91      
n = sample size =    1      
s = standard deviation =    10      
          
Thus,          
          
z =    0.5      
          
Thus, using a table/technology, the right tailed area of this is          
          
P(z >   0.5   ) =    0.308537539 [ANSWER]

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b)

We first get the z score for the critical value. As z = (x - u) sqrt(n) / s, then as          
          
x = critical value =    96      
u = mean =    91      
n = sample size =    10      
s = standard deviation =    10      
          
Thus,          
          
z =    1.58113883      
          
Thus, using a table/technology, the right tailed area of this is          
          
P(z >   1.58113883   ) =    0.056923149 (b)

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We first get the z score for the critical value. As z = (x - u) sqrt(n) / s, then as          
          
x = critical value =    96      
u = mean =    91      
n = sample size =    20      
s = standard deviation =    10      
          
Thus,          
          
z =    2.236067977      
          
Thus, using a table/technology, the right tailed area of this is          
          
P(z >   2.236067977   ) =    0.012673659 (c)

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