Question

CONFIDENCE INTERVAL PROJECT – Day 3

On this sheet, you will be calculating 95% Confidence Intervals for your data. Fill in all of the values for each piece, the formula, then show the full calculation for the CI. Write the CI in 2 different ways:

• In + notation

• In interval notation: ( ________ , ________ )

• When you record standard deviation- round to the nearest tenth.

Use the back of this sheet if extra space is needed.

PROPORTION CONFIDENCE INTERVAL:

p-hat = 11/30=.37

n = 30

z* =

Formula used:

Calculations:

95% Confidence Interval in both forms:

MEAN CONFIDENCE INTERVAL

x-bar =

s =

n =

z* =

Formula used:

Calculations:

95% Confidence Interval in both forms:

DATA TO USE TO ANSWER THOSE QUESTIONS:

Write out your question exactly as you will ask it to your sample. For example, “Do you have red hair, YES or NO?” Your question will most likely be a YES/NO question.

Question: Do you play fortnite?

Ask your question to at least 30 people. Be creative with this! You can set up a Facebook poll, Instagram poll, text friends, call friends, ask family/roommates, etc. Record their responses here as tallies:

          5 5 1

Yes: IIIII IIIII I

No: IIIII IIIII IIIII IIII

          5 5 5 4

Calculate the proportion of people who answered YES. Show your work below:

11/30 = 37%

What symbol would you use to represent that value? p Is it a statistic or parameter?

(Circle one) PARAMETER

MEAN CONFIDENCE INTERVAL

Write out your question exactly as you will ask it to your sample. For example, “How much do you weigh?”

Question: How many times a day on average do you play fortnite?

Ask your question to at least 30 people and record your results here.

0, 5, 2, 0 , 3 ,

1, 0 , 0, 7, 2,

0, 2, 0 , 0, 0,

4, 3, 0, 5, 2,

6, 0, 0, 2, 3,

0, 6, 2, 0 , 4

Calculate the average of your sample. Show your work below:

59/30= 1.96

Answer 1

The confidence interval for the population proportion is given by

Here for 95% confidence

Hence,

So the interval is

In interval notation we have

For the population mean confidence interval is given by

Here,    

for 95% confidence

Hence ,

So the interval is

That is