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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

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Sheila and Lenore were driving to their grandmother’s house. Lenore left 1 hour after Sheila. Sheila drove at a rate of 45mph, a
solong [7]

Answer:

It'll take 3 h before Lenore catch up to Sheila.

Step-by-step explanation:

To solve this problem we first need to calculate the relative speed between the two. Since they're going at the same direction we need to subtract their individual speeds if their directions were oposite we would have to sum their speeds. In this case we have:

relative speed = Lenore speed - Sheila speed

relative speed = 60 - 45 = 15 mph

Since Sheila left 1 h before Lenore and she drove at a rate of 45 mph, then she had covered a distance of:

distance = time*speed = 1*45 = 45 miles

Before Lenore left, so in order for Lenore to catch up to Sheila she needs to cover that distance at a relative speed of 15 mph.

time = distance/(relative speed) = 45/15 = 3 h

It'll take 3 h before Lenore catch up to Sheila.

4 0
3 years ago
The ratio of hotdogs to hamburgers is 8:3. if 272 hotdogs were sold how many hamburgers were sold.
Blababa [14]

Answer:

102 hamburgers

Step-by-step explanation:

Hotdogs: 8 272

Hamburgers: 3 HB

8/3=272/HB

3*272=8HB

816=8HB

HB=102

7 0
3 years ago
The speed of light is approximately 6.71 x 108 miles per hour. Express this number in standard form.
noname [10]

10^8=100000000

100000000x6.71=671,000,000

5 0
3 years ago
Si Martha retira de su cuenta el 10% para los transportes del mes. ¿Cuál es el nuevo saldo de la cuenta?
notsponge [240]

Respuesta:

0,9 veces

Explicación paso a paso:

Deje que la cantidad en la cuenta de Martha se denote como x, que es la cantidad en la cuenta = x

Porcentaje retirado para transporte = 10%

El porcentaje total siempre será del 100%

Por lo tanto, si se retira el 10%, entonces; el porcentaje restante es:

Porcentaje total: porcentaje gastado en transporte

(100% - 10%) * monto en cuenta

90% * x = 0,9 * x = 0,9x

Saldo de cuenta nueva = 0.9x

8 0
3 years ago
S = 2B + L. What do S, B, and L stand for?
notsponge [240]
Hi Jordyn! I think S is segment, B is base, and L is length. I hope this helped!
7 0
3 years ago
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