Basic Applied Statistics 90-707
Solutions to Practice Midterm 2

1.  
   1. (ii)
   2. (i)
   3. COUNT X has mean np=1600(0.02)=32 and sd square root of np(1-p) = 5.6
   4. PROPORTION has mean p=0.02 and sd square root of p(1-p)/n = 0.0035
   5. z=(0.026-0.02)/0.0035=+1.71
   6. (iii) because z is somewhat unusual
2.  
   1. 52.5-3(2.5)=45
   2. z=(59-52.5)/2.5=+2.6
   3. (i) because z is greater than 2.576
3.  
   1. (ii)
   2. mean of sample means is population mean 0.4, s.d. of sample means is population s.d. over square root of sample size, or 0.1
   3. (ii) shape of distribution of sample mean is approximately normal because the sample size (64) is fairly large
4.  
   1. (ii)
   2. (i)
5.  
   1. (x)
   2. (iii)
6.  
   1. 0.40 plus or minus 2 times square root of (0.40)(1-0.40)/96=0.40 plus or minus 0.10=(0.30, 0.50)
   2. (ii)
   3. (i)
   4. (iii)
   5. (ii)
7.  
   1. (ii)
   2. (vi)
   3. Ho: mu=13.7, Ha: mu not equal to 13.7
   4. (i) because 13.7 is well-contained in the confidence interval
   5. (iii)
   6. (iii)
8.  
   1. (i)
   2. (iv)
   3. (i)
   4. (iii)
   5. (i)

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