A vending machine is designed to dispense a mean of 7.6 oz of coffee into an​ 8-oz cup. If the standard deviation of the amount of coffee dispensed is 0.3 oz and the amount is normally​ distributed, find the percent of times the machine will dispense less than 7.57 oz.

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Answer:

46.02%

Step-by-step explanation:

We have been given that a vending machine is designed to dispense a mean of 7.6 oz of coffee into an​ 8-oz cup. The standard deviation of the amount of coffee dispensed is 0.3 oz and the amount is normally​ distributed.

We are asked to find the percent of times the machine will dispense less than 7.57 oz.

First of all, we will find the z-score corresponding to 7.57 using z-score formula.

[tex]z=\frac{x-\mu}{\sigma}[/tex], where,    

z = z-score,

x = Random sample score,

[tex]\mu[/tex]=  Mean,

[tex]\sigma[/tex]  = Standard deviation.    

[tex]z=\frac{7.57-7.6}{0.3}[/tex]

[tex]z=\frac{-0.03}{0.3}[/tex]

[tex]z=-0.1[/tex]

Now we will use normal distribution table to find the probability of z-score less than -0.1 that is [tex]P(z<-0.1)[/tex]

Using normal distribution table we will get:

[tex]P(z<-0.1)=0.46017[/tex]

Let us convert [tex]0.46017[/tex] into percentage as:

[tex]0.46017\times 100\%=46.017\%\approx 46.02\%[/tex]

Therefore, 46.02% of times the machine will dispense less than 7.57 oz.