1)
A)
(i)
P(Z<1.75) = NORMSDIST(1.75) = 0.9599
(ii)
(Z>-0.89) = 1- P(Z<-0.89) = 1 - NORMSDIST(-0.89) = 0.813267
(iii)
P(-0.89 < Z < 1.75) = P(Z<1.75) - P(Z<-0.89) = NORMSDIST(1.75) - NORMSDIST(-0.89) = 0.773208
B)
(i)
P(Zz= NORMSINV(0.26)
z= -0.643345405
(ii)
P(Z
z= NORMSINV(0.18)
z= -0.915365088
C)
(i)
P( X>30)
= 1 - P(X<30)
I know that, z = (X-mean)/(sd)
z1 = (30-28)/8)
z1= 0.2500
Hence,
P( X>30)
=1- P(Z<0.25)
1 - NORMSDIST(0.25)
0.401294
(ii)
P(9 < X < 29)
= P(X<29) - P(X<9)
I know that, z = (X-mean)/(sd)
z1 = (9-28)/8)
z1= -2.3750
z2 = (29-28)/8)
z2= 0.1250
Hence,
P(9 < X < 29)=
= P(Z<0.125) - P(Z<-2.375)
= NORMSDIST(0.125) - NORMSDIST(-2.375)
0.540964
(iii)
P(Z
z= NORMSINV(0.2)
z= -0.841621234
I know that, z = (X-mean)/sd
(X-mean)/sd = -0.8416
X= -0.8416*8+28
X= 21.27
D)
(i)
For large sample size, the sampling distribution of sample mean is normally distributed as per central limit theorem.
E(Xbar) = E(X)= 3.2
SD(xbar) = SD(X)/sqrt(n)= 1.3/SQRT(226) = 0.086474714
(ii)
P( X>4)
= 1 - P(X<4)
I know that, z = (X-mean)/(sd)
z1 = (4-3.2)/0.086474714)
z1= 9.2513
Hence,
P( X>4)
=1- P(Z<9.2513)
1 - NORMSDIST(9.2513)
0.000000
2)
A)
(i)
CI = mean +- z(a/2,n-1)*(sd/sqrt(n))
lower = 3 - 1.96*(1.22474487139159/sqrt(508))= 2.89
upper = 3 + 1.96*(1.22474487139159/sqrt(508))= 3.11
i am 95% confident that estimated population mean level of confidence in the Immigration Minister lie in the interval (2.89, 3.11).
(ii)
ho: the mean level of confidence in the Immigration Minister is 5
h1: the mean level of confidence in the Immigration Minister is not 5
mean= 3.00
sd= sqrt(var) 1.225
u= 5.00
n= 508.00
alpha= 5%
test statistic, z = (mean-u)/(sd/sqrt(n))
= (3-5)/(1.22474487139159/sqrt(508))
-36.8058
critical value, z(a/2) = z(0.05/2) = 1.960
p-value
2*(1-P(z<|z|)
2*(1-P(z
normsdist(abs(-36.8058))
0.0000
With (z=-36.8058, p<5%), null hypothesis is rejected at 5% level of significance.
Hence conclude that the mean level of confidence in the Immigration Minister is not 5.
b)
(ii)
X= 257
n= 856
p = X/n= 0.300
CI = p +- z(a/2)*sqrt(p*(1-p)/n)
lower =0.3-1.96*SQRT(0.3*(1-0.3)/856) = 26.9%
upper =0.3+1.96*SQRT(0.3*(1-0.3)/856) = 33.1%
i am 95% confident that estimated population proportion of people who picked “tightening immigration laws” as their first choice lie in the above interval.
(ii)
ho: the proportion of people who believe “tightening immigration laws” is the highest priority is 0.16
h1: the proportion of people who believe...