Answer:
a) 254.6 GPa
b) 140.86 GPa
Explanation:
a) Considering the expression of rule of mixtures for upper-bound and calculating the modulus of elasticity for upper bound;
Ec(u) = EmVm + EpVp
To calculate the volume fraction of matrix, 0.63 is substituted for Vp in the equation below,
Vm + Vp = 1
Vm = 1 - 0.63
Vm = 0.37
In the first equation,
Where
Em = 68 GPa, Ep = 380 GPa, Vm = 0.37 and Vp = 0.63,
The modulus of elasticity upper-bound is,
Ec(u) = EmVm + EpVp
Ec(u) = (68 x 0.37) + (380 x 0.63)
Ec(u) = 254.6 GPa.
b) Considering the express of rule of mixtures for lower bound;
Ec(l) = (EmEp)/(VmEp + VpEm)
Substituting values into the equation,
Ec(l) = (68 x 380)/(0.37 x 380) + (0.63 x 68)
Ec(l) = 25840/183.44
Ec(l) = 140.86 GPa
Answer:
a) Sample size = 1691
b) 95% Confidence Interval = (0.3696, 0.4304)
Explanation:
(a) How large a sample n should they take to estimate p with 2% margin of error and 90% confidence?
The margin of error is given by

Where z is the corresponding z-score for 90% confidence level
z = 1.645 (from z-table)
for p = 0.50 and 2% margin of error, the required sample size would be

(b) The advocacy group took a random sample of 1000 consumers who recently purchased this mobile phone and found that 400 were happy with their purchase. Find a 95% confidence interval for p.
The sample proportion is
p = 400/1000
p = 0.40
z = 1.96 (from z-table)
n = 1000
The confidence interval is given by

Therefore, we are 95% confident that the proportion of consumers who bought the newest generation of mobile phone were happy with their purchase is within the range of (0.3696, 0.4304)
What is Confidence Interval?
The confidence interval represents an interval that we can guarantee that the target variable will be within this interval for a given confidence level.
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All of them
explanation:
you don’t need one