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horrorfan [7]
3 years ago
7

A researcher wants to estimate the mean commute time of residents in Westchester County. The researcher samples 40 commuters and

find the mean commute time to be 25 minutes. Assume the population standard deviation for commute time is 12.5 minutes. Construct a 90% confidence interval for the mean commute time of residents in Westchester County. What is the Lower Bound of the confidence interval
Mathematics
1 answer:
Ksenya-84 [330]3 years ago
4 0

Answer:

21.759

Step-by-step explanation:

Given that :

Mean (m) = 25

Standard deviation (s) = 12.5

Sample size (n) = 40

α = 90%

The confidence interval is obtained using the relation:

Mean ± Zcritical * s/sqrt(n)

Zcritical at 90% confidence interval = 1.64

25 ± 1.64 * (12.5/sqrt(40))

Lower boundary : 25 - 1.64(1.9764235) = 21.75866546

Upper boundary : 25 + 1.64(1.9764235) = 28.24133454

(21.759, 28.241)

Hence, lower bound of confidence interval is : 21.759

You might be interested in
¿Qué interés produce s/ 72,000 al 5% anual en 1 año, 1 mes, 10 días?
PtichkaEL [24]

Answer: 3,988.8

Usaremos la fómula: I = C * i * n

I = 72 000 * 0.05 * (1 año + 1 mes + 10 día)

I = 72 000 * 0.05 * (1 + 0.08 + 0.0028)

I = 72 000 * 0.05 * 1.108

3,988.8

Step-by-step explanation:

Podemos obtener el interés que produce un capital con la siguiente fórmula:  

I = C * i * n

Ejemplo: Si queremos calcular el interés simple que produce un capital de 1.000.000 pesos invertido durante 5 años a una tasa del 8% anual. El interés simple se calculará de la siguiente forma:

I = 1.000.000 * 0,08 * 5 = 400.000

Si queremos calcular el mismo interés durante un periodo menor a un año (60 días), se calculará de la siguiente forma:

Periodo: 60 días = 60/360 = 0,16            

I = 1.000.000 * 0,08 * 60/360 =  13.333

Espero te ayude :3

3 0
3 years ago
(18) POINTS pLEASE HELP
JulijaS [17]

Answer:

(x-4)(x-3)

Step-by-step explanation:

x^{2} -7x+12\\

multiply 1 and 12= 12

find two numbers that multiply to get twelve AND add together to get -7(the middle number)

the two numbers are -3 and -4 (they add up to get -7 AND multiply together to get 12)

plug in these numbers for -7x

x^{2} -3x-4x+12

x(x-3)-4(x-3)

the bolded is the first binomial and the second binomial is in the parenthesis.

(x-4)(x-3)

I hope this helps!

5 0
3 years ago
Read 2 more answers
Delta math help me pleaseeeeeee
lozanna [386]
The answer is 5,12,14
7 0
3 years ago
Read 2 more answers
F
galina1969 [7]
It’s F because I took the test
8 0
3 years ago
Use the Midpoint Rule and the given data to estimate the value of the integral I. (Give the answer to two decimal places.)
svlad2 [7]

Answer:

a) integral = 24.72

b) |Error| ≤ 0.4267

Step-by-step explanation:

a)

The integral:

\int_{0}^{3.2} f(x) dx

can be  approximated with the midpoint rule, as follows:

6.7*(0.8 - 0.0) + 8.9*(1.6 - 0.8) + 6.9*(2.4-1.6) + 8.4*(3.2 - 2.4) = 24.72

(that is, all the intervals are 0.8 units length and f(x) is evaluated in the midpoint of the interval)

b)The error bound for the midpoint rule with <em>n</em> points is:

|Error| ≤ K*(b - a)^3/(24*n^2)

where <em>b</em> and are the limits of integration of the integral and K = max |f''(x)|

Given that -5 ≤ f''(x) ≤ 1, then K = 5.  Replacing into the equation:

|Error| ≤ 5*(3.2 - 0)^3/(24*4^2) = 0.4267

5 0
3 years ago
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