Question

The true percentage of left-handed people is 13% (p = .13)

1) a. If we survey two hundred people, how many left handers do you expect to survey?

b. If you repeat this survey, will you always get this number of left-handers (the
expectation)? Why or why not?

c. What is the spread (standard deviation) of the sample proportions?

d. Use the empirical rule to describe where we expect sample proportions to lie if we
repeated this survey (with size of 200 people) over and over again

68% of sample proportions would lie between ______________and _____________

95% of sample proportions would lie between _____________and______________

99.7% of sample proportions would lie between _____________and______________

Answer 1

1.

Suppose, random variable X denotes number of left-handed people among 200 people.

Given,

(a)

Number of people surveyed

(b)

If we repeat the survey, we shall not always get this number (26) of left-handers.

We are performing survey over different sample and so observed number of left-handers differs.

(c)

Variance is given by

So, standard deviation is given by

(d)

For level of significance ,

confidence interval is

68%

For , and confidence interval is

i.e.

i.e.

95%

For , and confidence interval is

i.e.

i.e.

99.7%

For , and confidence interval is

i.e.

i.e.