The amount of fill in a half-liter (500 ml) soft drink bottle is normally distributed. The process has a standard deviation of 5 ml. The mean is adjustable.

a. Where should the mean be set to ensure a 95 percent probability that a half-liter bottle will not be underfilled?
b. Where should the mean be set to ensure a 99 percent probability that a half-liter bottle will not be underfilled?
c. Where should the mean be set to ensure a 99.9 percent probability that a half-liter bottle will not be underfilled?

Respuesta :

Answer:

A. 491.775

B. 488.37

C. 484.55

Step-by-step explanation:

A. 100-95 = 5

thus

[tex]\frac{5}{100} = 0.05[/tex]

using the formula;

[tex]Z_{0.05} = \frac{X- \mu}{\sigma}[/tex]

where X = 500

         μ = mean

         σ = 5 (standard deviation)

[tex]\mu= X - Z_{0.05}\sigma[/tex]

   = 500 - 1.645(5)

   = 491.775

(please note that [tex]Z_{}0.05[/tex] = 1.645 from the standard normal distribution table )

B. similarly,  following the above method we have

100 - 99 = 1

1/100 = 0.01

from the standard normal distribution table [tex]Z_{0.01} = 2.326[/tex]

 μ = X - [tex]Z_{0.01}[/tex]σ

    = 500 - 2.326(5)

    = 488.37

C. 100 - 99.9 = 0.1

0.1/100 = 0.001

from the standard normal distribution [tex]Z_{0.001} = 3.09[/tex]

μ = X -  [tex]Z_{0.001}[/tex]σ

   = 500 - 3.09(5)

    = 484.55

Part(a): The required mean is [tex]508.225[/tex]

Part(b): The required mean is [tex]511.65[/tex]

Part(b): The required mean is [tex]515.45[/tex]

Mean:

Mean is the average of the given numbers and is calculated by dividing the sum of given numbers by the total number of numbers.  

Let [tex]X[/tex] denotes the amount of fill-in half-liter soft drink and follows a normal distribution with parameters.

Part(a):

Calculating the mean be set to ensure a 95% of probability is,

[tex]P(X\ge500)=0.95\\1-P(Z < \frac{500-\mu}{5} )=0.95\\\frac{500-\mu}{5} =0.05\\\mu=508.225[/tex]

Part(b):

Calculating the mean be set to ensure a 99% of probability is,

[tex]P(X \ge 500)=0.99\\1-P(Z < \frac{500-\mu}{5} )=1-0.99\\\mu=511.65[/tex]

Part(c):

Calculating the mean be set to ensure a 99.9% of probability is,

[tex]P(X\ge500)=0.999\\1-P(Z < \frac{500-\mu}{5} )=0.999\\\frac{500-\mu}{5}=0.001\\ \mu=515.45[/tex]

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