If the standard deviation for lifetimes of vacuum cleaners is estimated to be 400 hours, how large a sample must be taken in order to be 93% confident that the marge of error will not exceed 50 hours?

I know that n+(za/2)2 standard devation squared/the margin of error squared. What I don't know is how do I get the 93% confidence which is the z a/2 squared

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Posted on Jan 02, 2017

About 5.23. If this is homework, be sure to show your work.

Jun 25, 2014 | Office Equipment & Supplies

Population size:4

Mean (?): 23.45

Standard deviation (?): 4.5986411036305

Mean (?): 23.45

Standard deviation (?): 4.5986411036305

Mar 07, 2014 | Office Equipment & Supplies

If you mean the standard deviation, there are two shifted keys on the third row marked with a lower-case Greek sigma. sigma_xn is the population standard deviation and sigma_xn-1 is the sample standard deviation.

Nov 12, 2013 | Texas Instruments TI-30XA Calculator

Here are the capabilities of the Casio calculators.

The screen captures may not look like ones taken from the FX-7400G

plus display but the instructions are accurate.

In stat enter the values in List1 and the frequencies in List2**(if doing paired variable statistics)**

Press the key corresponding to the CALC tab

Press the 1-var tab and you get the results as seen on the screen with title 1-variable.

Other screens show some two-variable stats or regressions.

Use you knowledge of sample standard deviations and

population standard deviation to select which is relevant to your case.

They are given by xsigma-n and xSigma n-1

The screen captures may not look like ones taken from the FX-7400G

plus display but the instructions are accurate.

In stat enter the values in List1 and the frequencies in List2

Press the key corresponding to the CALC tab

Press the 1-var tab and you get the results as seen on the screen with title 1-variable.

Other screens show some two-variable stats or regressions.

Use you knowledge of sample standard deviations and

population standard deviation to select which is relevant to your case.

They are given by xsigma-n and xSigma n-1

Aug 15, 2011 | Casio FX-7400G Plus Calculator

The TI-30XA does not have to be switched to a statistics mode, the operations are available all the time. The choice of operations are somewhat limited; the calculator offers statistics functions for one dimensional data sets only (no linear interpolation of (x,y) value pairs, for example):

Example: calculate the average and standard deviation of the set { 3, 4, 5, 5, 5, 5, 6 }.

- [2nd] [CSR] - erase statistics data
- [] - add a number to the sample set
- [2nd] [] - remove a number from the sample set
- [2nd] [FRQ] - multiple entry of the same sample value
- [2nd] [n] - sample set size
- [2nd] [] - sum of all sample elements
- [2nd] [] - sum of the squares of all sample elements
- [2nd] [] - average of the sample set
- [2nd] [] - standard deviation (sample set is a complete set)
- [2nd] [] - standard deviation (sample set is a subset of a larger set)

Example: calculate the average and standard deviation of the set { 3, 4, 5, 5, 5, 5, 6 }.

- [2nd] [CSR] - erase stat memory
- 3 [] 4 [] 5 [2nd] [FRQ] 4 [] 6 [] - enter the data, note the use of [2nd] [FRQ] to enter the four occurrences of "5". Entering 5 [] four times would have done the same.
- [2nd] [] - display the average of the set, (4.714...)
- [2nd] [] - display the standard deviation of the set (0.8806...)

Jan 25, 2011 | Texas Instruments TI-30XA Calculator

Example: Enter the following x variables, and determine the sample and population standard deviations.

**x** = {1,2,3}

- Press [DATA] and begin to enter the data as indicated into the L1, L2 or L3 lists. To input a data point, type the value and press [ENTER]. Press the down arrow key to move on to the next data point.
- Press [2nd], [STAT], and then choose 1-VAR.
- For the "DATA" option, choose the listname the data is stored in (L1, L2 or L3). For the "FRQ" option, choose "ONE" since this data does not include a frequency list.
- Arrow down to "CALC" and press [ENTER].
*Answers should be as follows:*

3:Sx (Sample Standard Deviation) = 1

4:sx (Population Standard Deviation) = 0.816497 - Press [2nd] [MODE] to exit STAT mode.

Oct 20, 2010 | Texas Instruments TI30XS Scientific...

Yes. The sample standard deviation is 2nd [sigma x n-1] and the population standard deviation is 2nd [sigma x n].

Apr 02, 2010 | Texas Instruments TI-30XA Calculator

34 σ+

39 σ+

32 σ+

36 σ+

30 σ+

33 σ+

2nd ÷ (σxn)

39 σ+

32 σ+

36 σ+

30 σ+

33 σ+

2nd ÷ (σxn)

Jun 02, 2009 | Texas Instruments TI-30XA Calculator

Press 2ND [CSR] to clear the stat data.

For each data point, enter the number followed by SIGMA+

If you have grouped data, enter the number followed by 2ND [FRQ] followed by the frequency then SIGMA+

Press 2ND [sigma x n] for the population standard deviation or 2ND [sigma x n-1] for the sample standard deviation.

For each data point, enter the number followed by SIGMA+

If you have grouped data, enter the number followed by 2ND [FRQ] followed by the frequency then SIGMA+

Press 2ND [sigma x n] for the population standard deviation or 2ND [sigma x n-1] for the sample standard deviation.

May 25, 2009 | Texas Instruments TI-30X-IISTK Scientific...

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