A cracker manufacturer’s boxes have been found to have a standard deviation of 10 grams and a mean of 412 grams.

How many grams should be specified (printed on the box) to ensure that 95 percent of the boxes will contain more than this weight?

Respuesta :

Answer:

395.55 grams should be specified to ensure that 95 percent of the boxes will contain more than this weight.

Explanation:

We are given the following information in the question:

Mean, μ = 412 grams

Standard Deviation, σ = 10 grams

Formula:

[tex]z_{score} = \displaystyle\frac{x-\mu}{\sigma}[/tex]  

We have to find the value of x such that the probability is 0.95

P(X > x)  

[tex]P( X > x) = P( z > \displaystyle\frac{x - 412}{10})=0.95[/tex]  

[tex]= 1 -P( z \leq \displaystyle\frac{x - 412}{10})=0.95 [/tex]  

[tex]=P( z \leq \displaystyle\frac{x - 412}{10})=0.05 [/tex]  

Calculation the value from standard normal z table, we have,  

[tex]\displaystyle\frac{x - 412}{10} = -1.645\\\\x = 395.55[/tex]  

Hence, 395.55 grams should be specified to ensure that 95 percent of the boxes will contain more than this weight.