Basic Applied Statistics 200
Solutions to Practice Midterm 2

 (ii)
 (i)
 COUNT X has mean np=1600(.02)=32 and sd square root of np(1p) = 5.6
 PROPORTION has mean p=.02 and sd square root of p(1p)/n = .0035
 z=(.026.02)/.0035=+1.71
 (iii) because z is somewhat unusual

 52.53(2.5)=45
 z=(5952.5)/2.5=+2.6
 (i) because z is greater than 2.576

 (ii)
 mean of sample means is population mean .4, s.d. of sample means is
population s.d. over square root of sample size, or .1
 (ii) shape of distribution of sample mean is approximately normal
because the sample size (64) is fairly large

 (ii)
 (i)

 (x)
 (iii)

 0.40 plus or minus 2 times square root of (0.40)(10.40)/96=0.40 plus or
minus 0.10=(0.30, 0.50)
 (ii)
 (i)
 (iii)
 (ii)

 (ii)
 (vi)
 Ho: mu=13.7, Ha: mu not equal to 13.7
 (i) because 13.7 is wellcontained in the confidence interval
 (iii)
 (iii)

 (i)
 (iv)
 (i)
 (iii)
 (i)
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