ASAP. Just circle answers please!

Part II: Problem Set Assignment for Confidence Intervals - Sections 7-1 & 7-2

GUIDANCE: See the handout on Confidence Intervals at pgs. 5-8, 11-15

The Genetics and IVF Institute conducted a clinical trial of the Y-SORT Method

designed to increase the probability of couples conceiving a boy child. Assume

that n = 291 babies were born with this X-SORT method and the x = 239 of them

were boys.

(Q#1a) What proportion: = x/n, were boys

(Q#1b) What is the standard deviation for this estimated proportion:

=

(Q#1c) What is the Z-Score(1-) for a 99% Confidence Level : Z_/2 = ?

(Q#1d) What is the Margin of Error for this scenario: E = Z_/2 *

(Q#1e) Construct a 99% Confidence Interval for the proportion of boys born to

parents using the Y-SORT method: E < p < + E

Consider a group of n = 64 credit card applicants. Assume that that the

distribution of credit scores in the population is normal as follows but with an

unknown population mean:

X_i ~ N [ _X = ____ pts. , _X = 68 pts. ]

The average or mean credit score in the group of applications was: = 677 pts.

(Q#2a) What is the standard deviation for this estimated sample mean:

(Q#2b) What is the Z-Score(1-) for a 90% Confidence Level : Z_/2 = ?

(Q#2c) What is the Margin of Error in this case: E = Z_/2 *

(Q#2d) Construct a 90% Confidence Interval for the average or mean score for

the group of n = 64 credit card applicants: E < _X < + E

Determine Optimal Sample Size = n

GUIDANCE: See the handout on Confidence Intervals at pgs. 15-17

A political poll taker believes that a forthcoming poll will reveal the following:

= .52 (52%) of likely voters will support Donald Trump in next years election.

= .48 (48%) of likely voters will support Joe Biden in next years election.

The pollster want to construct a 95% (=.05) confidence interval for this with a

Margin of Error, E = .02 (2%). How large a sample size = n will be needed to

achieve this level of accuracy?

(Q#3a) What is the Z-Score for a 1- = 95%? Z_/2 = ?

(Q#3b) Combining the previous answers and assuming that E = .02 what is the

needed sample size? Recall this formula from the handout:

n = [ Z_/2 / E ]² * { }