Question

In: Statistics and Probability

Construct two 95% confidence intervals for each sample. SD = $35,989.61 Apply the population standard deviation...

Construct two 95% confidence intervals for each sample.

SD = $35,989.61

Apply the population standard deviation (σ) in the formula to form z-distribution since the population standard deviation is known.

Loan Amount Type Sample 1
$    30,500.00 Commercial
$    78,500.00 Commercial
$    90,000.00 Commercial
$    19,000.00 Commercial
$    36,000.00 Commercial
$    89,500.00 Commercial
$    22,000.00 Commercial
$    65,000.00 Commercial
$ 109,000.00 Commercial
$     5,500.00 Commercial
$    93,500.00 Commercial
$     6,000.00 Commercial
$    85,500.00 Commercial
$    98,000.00 Commercial
$    57,000.00 Commercial
$    59,000.00 Commercial
$     8,500.00 Commercial
$     9,000.00 Commercial
$    16,000.00 Commercial
$    71,000.00 Commercial
$    79,000.00 Commercial
$    32,500.00 Commercial
$     3,500.00 Commercial
$    95,500.00 Commercial
$    75,500.00 Commercial
$    90,500.00 Commercial
$    25,500.00 Commercial
$ 122,000.00 Commercial
$    27,500.00 Commercial
$ 112,500.00 Commercial
$    91,000.00 Commercial
$ 107,500.00 Commercial
$    75,500.00 Commercial
$    73,000.00 Commercial
$    17,500.00 Commercial
$    91,000.00 Commercial
$    23,500.00 Commercial
$ 111,000.00 Commercial
$    66,500.00 Commercial
$    21,000.00 Commercial
$    21,500.00 Commercial
$    12,000.00 Commercial
$    45,000.00 Commercial
$ 123,000.00 Commercial
$    18,500.00 Commercial
$     6,500.00 Commercial
$ 118,500.00 Commercial
$    91,000.00 Commercial
$    23,000.00 Commercial
$    38,500.00 Commercial
$    96,000.00 Commercial
$    91,000.00 Commercial
$    16,500.00 Commercial
$    36,000.00 Commercial
$    96,000.00 Commercial
$    96,500.00 Commercial
$    86,500.00 Commercial
$    46,000.00 Commercial
$    19,000.00 Commercial
$    84,500.00 Commercial
$    57,000.00 Commercial
$    29,000.00 Commercial
$ 124,500.00 Commercial
$    12,000.00 Commercial
$    50,000.00 Commercial
$    66,000.00 Commercial
$    48,000.00 Commercial
$    44,000.00 Commercial
$    92,000.00 Commercial
$    16,000.00 Commercial
$    39,500.00 Commercial
$     9,000.00 Commercial
$    43,000.00 Commercial
$    91,000.00 Commercial
$    73,000.00 Commercial
$    90,500.00 Commercial
$    64,500.00 Commercial
$ 112,500.00 Commercial
$    82,500.00 Commercial
$    86,500.00 Commercial
$    10,000.00 Commercial
$    31,500.00 Commercial
$    41,500.00 Commercial
$    39,000.00 Commercial
$    40,500.00 Commercial
$    69,000.00 Commercial
$    66,500.00 Commercial
$    60,000.00 Commercial
$    54,000.00 Commercial
$ 122,000.00 Commercial
$    44,000.00 Commercial
$    33,000.00 Commercial
$    97,000.00 Commercial
$ 103,000.00 Commercial
$    97,500.00 Commercial
$ 110,500.00 Commercial
$    21,500.00 Commercial
$ 116,000.00 Commercial
$    72,000.00 Commercial
$    66,500.00 Commercial
$    79,000.00 Commercial
$    36,000.00 Commercial
$    84,000.00 Commercial
$    99,000.00 Commercial
$     4,000.00 Commercial
$ 115,000.00 Commercial
$    86,000.00 Commercial
$    42,000.00 Commercial
$ 117,000.00 Commercial
$    18,500.00 Commercial
$ 123,000.00 Commercial
$ 109,000.00 Commercial
$    37,500.00 Commercial
$    53,500.00 Commercial
$    36,000.00 Commercial
$    62,000.00 Commercial
$    44,500.00 Commercial
$     3,500.00 Commercial
$    56,500.00 Commercial
$    82,000.00 Commercial
$     7,500.00 Commercial
$    94,000.00 Commercial
$    89,000.00 Commercial
$     6,500.00 Commercial
$     9,500.00 Commercial
$    89,000.00 Commercial
$     6,500.00 Commercial
$    95,500.00 Commercial
$    23,500.00 Commercial
$    59,000.00 Commercial
$    31,000.00 Commercial
$    22,500.00 Commercial
$    35,000.00 Commercial
$    59,000.00 Commercial
$    31,500.00 Commercial
$    40,500.00 Commercial
$    73,500.00 Commercial
$    21,500.00 Commercial
$    45,000.00 Commercial
$    79,500.00 Commercial
$ 110,500.00 Commercial
$ 112,000.00 Commercial
$    12,500.00 Commercial
$ 105,000.00 Commercial
$    92,500.00 Commercial
$    65,000.00 Commercial
$     7,500.00 Commercial
$     6,000.00 Commercial
$    73,500.00 Commercial
$    98,500.00 Commercial
$    59,500.00 Commercial
$    31,000.00 Commercial
$    67,000.00 Commercial
$    28,500.00 Commercial
$    63,500.00 Commercial
$ 108,500.00 Commercial
$ 101,000.00 Commercial
$ 120,000.00 Commercial
$    63,500.00 Commercial
$    74,000.00 Commercial
$    40,000.00 Commercial
$ 109,500.00 Commercial
$ 114,500.00 Commercial
$    89,000.00 Commercial
$    86,000.00 Commercial
$    69,500.00 Commercial
$    85,000.00 Commercial
$     5,500.00 Commercial
$ 112,500.00 Commercial
$    95,000.00 Commercial
$    70,500.00 Commercial
$    33,000.00 Consumer
$    89,500.00 Consumer
$    40,000.00 Consumer
$    76,000.00 Consumer
$    72,500.00 Consumer
$ 123,500.00 Consumer
$     9,000.00 Consumer
$     6,500.00 Consumer
$ 113,500.00 Consumer
$    86,000.00 Consumer
$ 108,500.00 Consumer
$    24,500.00 Consumer
$    78,000.00 Consumer
$    70,000.00 Consumer
$ 125,000.00 Consumer
$    32,500.00 Consumer
$    15,000.00 Consumer
$    16,000.00 Consumer
$    40,500.00 Consumer
$ 101,000.00 Consumer
$    12,000.00 Consumer
$    33,000.00 Consumer
$    50,000.00 Consumer
$    81,500.00 Consumer
$    17,500.00 Consumer
$    45,000.00 Consumer
$    56,500.00 Consumer
$    39,000.00 Consumer
$ 123,500.00 Consumer
$ 118,000.00 Consumer
$    46,500.00 Consumer
$    49,000.00 Consumer
$ 105,500.00 Consumer
$    15,500.00 Consumer
$    94,500.00 Consumer
$    20,000.00 Consumer
$    83,500.00 Consumer
$    74,000.00 Consumer
$    33,000.00 Consumer
$ 122,500.00 Consumer
$    64,000.00 Consumer
$    11,500.00 Consumer
$ 124,000.00 Consumer
$    33,000.00 Consumer
$    14,500.00 Consumer
$    11,500.00 Consumer
$    83,500.00 Consumer
$ 101,000.00 Consumer
$    62,000.00 Consumer
$    75,500.00 Consumer
$    18,500.00 Consumer
$    56,000.00 Consumer
$    66,500.00 Consumer
$    42,500.00 Consumer
$    44,500.00 Consumer
$    72,500.00 Consumer
$    20,000.00 Consumer
$    37,500.00 Consumer
$     5,500.00 Consumer
$    94,000.00 Consumer
$    98,000.00 Consumer
$    94,000.00 Consumer
$    57,500.00 Consumer
$    30,000.00 Consumer
$ 120,500.00 Consumer
$     8,000.00 Consumer
$ 108,500.00 Consumer
$     6,000.00 Consumer
$ 106,500.00 Consumer
$    31,000.00 Consumer
$    52,500.00 Consumer
$    58,500.00 Consumer
$ 105,000.00 Consumer
$     4,500.00 Consumer
$    76,500.00 Consumer
$    72,500.00 Consumer
$ 107,000.00 Consumer
$    98,500.00 Consumer
$    87,000.00 Consumer
$ 118,500.00 Consumer
$ 105,000.00 Consumer
$    64,500.00 Consumer
$    16,500.00 Consumer
$    77,500.00 Consumer
$    40,000.00 Consumer
$    16,000.00 Consumer
$ 111,000.00 Consumer
$    41,000.00 Consumer
$     7,000.00 Consumer
$    35,000.00 Consumer
$    90,000.00 Consumer
$    21,500.00 Consumer
$    71,500.00 Consumer
$ 115,500.00 Consumer
$    17,500.00 Consumer
$     8,500.00 Consumer
$    72,000.00 Consumer
$    56,500.00 Consumer
$    45,500.00 Consumer
$    49,000.00 Consumer
$    43,500.00 Consumer
$ 124,000.00 Consumer
$    41,000.00 Consumer
$    10,500.00 Consumer
$ 102,000.00 Consumer
$ 113,500.00 Consumer
$    36,500.00 Consumer
$    15,000.00 Consumer
$ 114,500.00 Consumer
$ 121,500.00 Consumer
$    76,000.00 Consumer
$    64,500.00 Consumer
$    27,000.00 Consumer
$    77,500.00 Consumer
$    63,500.00 Consumer
$    76,500.00 Consumer
$    48,500.00 Real Estate
$ 117,500.00 Real Estate
$    57,000.00 Real Estate
$    82,000.00 Real Estate
$ 118,000.00 Real Estate
$    70,000.00 Real Estate
$ 106,000.00 Real Estate
$    56,500.00 Real Estate
$    39,000.00 Real Estate
$ 119,000.00 Real Estate
$    93,000.00 Real Estate
$    11,000.00 Real Estate
$    66,000.00 Real Estate
$    19,500.00 Real Estate
$ 106,500.00 Real Estate
$    23,000.00 Real Estate
$    98,500.00 Real Estate
$    30,500.00 Real Estate
$ 120,500.00 Real Estate
$    82,500.00 Real Estate
$ 102,500.00 Real Estate
$    22,000.00 Real Estate
$ 112,500.00 Real Estate
$ 112,000.00 Real Estate
$    24,500.00 Real Estate
$    57,000.00 Real Estate
$    74,000.00 Real Estate
$ 102,500.00 Real Estate
$    29,000.00 Real Estate
$    81,500.00 Real Estate
$    34,000.00 Real Estate
$ 112,000.00 Real Estate
$    68,000.00 Real Estate
$ 109,500.00 Real Estate
$    32,000.00 Real Estate
$    32,000.00 Real Estate
$    99,000.00 Real Estate
$    93,500.00 Real Estate
$    95,000.00 Real Estate
$    89,000.00 Real Estate
$    83,000.00 Real Estate
$ 117,000.00 Real Estate
$    58,000.00 Real Estate
$    12,500.00 Real Estate
$ 102,500.00 Real Estate
$    81,000.00 Real Estate
$ 125,000.00 Real Estate
$    63,500.00 Real Estate
$ 107,500.00 Real Estate
$     9,000.00 Real Estate
$ 110,500.00 Real Estate
$    64,500.00 Real Estate
$    69,500.00 Real Estate
$    71,000.00 Real Estate
$    81,500.00 Real Estate
$    89,000.00 Real Estate
$    61,500.00 Real Estate
$    65,000.00 Real Estate
$ 123,000.00 Real Estate
$    65,000.00 Real Estate
$    45,000.00 Real Estate
$    25,000.00 Real Estate
$    17,000.00

Real Estate

Solutions

Expert Solution

GIVEN:

Population standard deviation

When the population standard deviation is known, the formula for a confidence interval (CI) for a population mean is given by,

  

where is the sample mean.

​ is the population standard deviation.

n is the sample size, and

z* represents the appropriate z*-value from the standard normal distribution for desired confidence level.

For the given problem the z*-value from the standard normal distribution for 95% confidence level is 1.96.

SAMPLE 1 (COMMERCIAL TYPE):

Let us consider sample 1 (commercial type)

Total number of observations from sample 1 (n) = 171

The sample mean is defined as the average of n observations from the sample and it is considered to be the estimate of pupulation mean.

I have used excel function to find the sample mean given by,

   "=AVERAGE(select array of values from sample 1)"

Thus the mean of sample 1

Population standard deviation

The z*-value from the standard normal distribution for 95% confidence level is 1.96.

The 95% confidence interval (CI) for a population mean is given by,

Thus 95% confidence interval for mean loan amount in the sample 1 (Commercial Type) is .

SAMPLE 2 (CONSUMER TYPE):

Let us consider sample 2 (consumer type)

Total number of observations from sample 2 (n) = 116

The sample mean is defined as the average of n observations from the sample and it is considered to be the estimate of pupulation mean.

I have used excel function to find the sample mean given by,

   "=AVERAGE(select array of values from sample 2)"

Thus the mean of sample 2 ​

Population standard deviation

The z*-value from the standard normal distribution for 95% confidence level is 1.96.

The 95% confidence interval (CI) for a population mean is given by,

Thus 95% confidence interval for mean loan amount in the sample 2 (Consumer Type) is   

SAMPLE 3 (REAL ESTATE TYPE):

Let us consider sample 3 (Real estate type)

Total number of observations from sample 3 (n) = 63

The sample mean is defined as the average of n observations from the sample and it is considered to be the estimate of pupulation mean.

I have used excel function to find the sample mean given by,

   "=AVERAGE(select array of values from sample 2)"

Thus the mean of sample 3 ​

Population standard deviation

The z*-value from the standard normal distribution for 95% confidence level is 1.96.

The 95% confidence interval (CI) for a population mean is given by,

Thus 95% confidence interval for mean loan amount in the sample 3 (Real Estate Type) is ​   


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