2.A family dines in a popular franchise restaurant. They plan to use a coupon that will give them a discount of 15% off of their
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Answer:
[0.7210,0.8189] = [72.10%, 81.89%]
Step-by-step explanation:
The sample size is
n = 200
the proportion is
p = 154/200 = 0.77
<em>Since both np ≥ 10 and n(1-p) ≥ 10 </em>
<em>We can approximate this discrete binomial distribution with the continuous Normal distribution. As the sample size is large enough, not applying the continuity correction factor makes no significant difference. </em>
The approximation would be to a Normal curve with this parameters:
<em>Mean </em>
p = 0.77
<em>Standard deviation </em>
The 90% confidence interval for the proportion would be then
where is the 10% critical value for the Normal N(0,1) distribution , this is a value such that the area under the N(0,1) curve outside the interval
is 10%=0.1
We can either use a table, a calculator or a spreadsheet to get this value.
In Excel or OpenOffice Calc we use the function
<em>NORMSINV(0.95) and we get a value of 1.645 </em>
The 90% confidence interval for the proportion is then
This means there is a 90% probability that the proportion of people who watch educational television is between 72.10% and 81.89%
If the television company wanted to publicize the proportion of viewers, do you think it should use the 90% confidence interval?
Yes, I do.
A.
If she will choose 8 from 12 photos, the total number of ways she can choose is given by a combination of 12 choose 8, since the order of the photos doesn't matter.
The formula for a combination of n choose p is:
For n = 12 and p = 8, we have:
So there are 495 ways.
B.
If she wants to arrange the 12 photos, the total number of ways is given by the factorial of 12:
There are 479,001,600 ways.
C.
Since 10 photos already have specific places, we need to calculate the number of ways to arrange the other two photos in the two remaining places.
In this case, there are only 2 ways of organizing the remaining two photos:
Photo 1 first, photo 2 last, or photo 1 last and photo 2 first.