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lapo4ka [179]
3 years ago
12

Direct mail advertisers send solicitations​ ("junk mail") to thousands of potential customers in the hope that some will buy the

​ company's product. The response rate is usually quite low. Suppose a company wants to test the response to a new flyer and sends it to 1030 people randomly selected from their mailing list of over​ 200,000 people. They get orders from 103 of the recipients.
Required:
Create a 95% confidence interval for the percentage of people the company contacts who may buy something. (Show your work. Step by step)
Mathematics
1 answer:
harina [27]3 years ago
5 0

Answer:

The interval is (.0817, .118).

Step-by-step explanation:

Let's make this interval! The easy way is to go to STAT->TEST->A, 1-prop z-int, but I will show the long way.

<u>1. Conditions</u>

First we must check the conditions.

<em>Randomization condition: </em>The sample is given to be random, so we can assume independence.

<em>Success/failure condition: </em>Both np>10 and nq>10 must be met.

  • np = 1030(103/1030) = 103 ✓
  • nq = 1030(927/1030) = 927 ✓

<em>10% condition: </em>The sample cannot be greater than 10% of the population.

  • 10n < N, 10(1030) < 200000 ✓

All conditions are met, so we can use <u>a 1-proportion z-interval</u> to represent the data.

<u></u>

<u>2. Mechanics</u>

<u>Find </u>\hat{p}<u>, the sample proportion.</u>

103/1030 = .1

\hat{q}, then, the probability of not p, is 1 - .1 = .9

<u>Find z* (z star), the critical z-value.</u>

You can do this on your calculator using 2nd->VARS->3 (or you can memorize it - it's 1.96. Winky face.) This is called the invNorm function, that takes the left side area under the normal curve. But what do we plug in to the invNorm function?

invNorm(.975) = 1.96

<u>Plug values into the equation.</u>

\hat{p} ± z*\sqrt{\frac{\hat{p}\hat{q}}{n} }

.1 ± 1.96\sqrt{\frac{.1*.9}{1030} }

.1 ± 1.96(.00935)

.1 - .0183 = .0817

.1 + .0183 = .118

(.0817, .118)

<u>3. Conclusion</u>

Based on this sample, we are 95% confident that the proportion of people the company contacts who may buy something is between .0817 and .118. That isn't very likely, but maybe they'll make a little profit!

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An example should make this clear.

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Alborosie

Answer: 8t+581

Step-by-step explanation:

<h3> The complete exercise is: "Omar works as a tutor for $15 an hour and as a waiter for $7 an hour. This month, he worked a combined total of 83 hours at his two jobs. Let "t" be the number of hours Omar worked as a tutor this month. Write an expression for the combined total dollar amount he earned this month."</h3><h3 />

Let be "t" the number of hours Omar worked as a tutor this month and "w" the number of hours Omar worked as a waiter this month.

Based on the data given in the exercise, you know that Omar worked a combined total of 83 hours this month.

Then, you can represent the number of hours he worked as a waiter this month with this equation:

w=83-t

Since he earns  $15 per hour working has a tutor and $7 per hour working as a waiter, you can write the following expresion to represent the total money earned:

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Since w=83-t, you can substitute it into the expression and then simplify it in order to find the final expression that represents the total amount of money Omar earned this month.

This is:

15t+7(83-t)=15t+581-7t=8t+581

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Answer:

~~

Step-by-step explanation:

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Read more on Brainly.com - brainly.com/question/12450752#readmore

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