The distribution of the number of moths captured per night by a certain moth trap is approximately normal with mean 103. If 28 percent of the captures fall below 76 per night, which of the following equations can be used to find σσ, the standard deviation of the distribution?
A) 0.28= 103-76/ σ
B) 0.28= 76- 103/ σ
C) -0.58= 103-76/ σ
D) -0.58= 103-76/σ
E) 0.58= 76-103/ σ

Respuesta :

Answer:C)   [tex]0.58=\dfrac[103-76}{\sigma}[/tex]

Step-by-step explanation:

Given : The distribution of the number of moths captured per night by a certain moth trap is approximately normal with  [tex]\mu=103[/tex].

Also,  28 percent of the captures fall below 76 per night, which of the following equation,

On z-table , the z-value corresponding to the p-value of 28% is -0.58.

Since formula for z-score : [tex]z=\dfrac{x-\mu}{\sigma}[/tex] , where x is random variable and [tex]\sigma[/tex] is standard deviation.

For the current situation, the formula becomes with values  [tex]\mu=103, x=76 , \&\ z=-0.58[/tex] as

[tex]-0.58=\dfrac{76-103}{\sigma}\\\\0.58=\dfrac[103-76}{\sigma}[/tex]

Hence, the equations can be used to find σσ, the standard deviation of the distribution :-

[tex]0.58=\dfrac[103-76}{\sigma}[/tex]

Equation to find the standard deviation of the distribution is;

-0.58 = (76 - 103)/σ

In solving this question, we will make use of z-distribution table and also the z-score formula.

We are given;

Mean; μ = 103

Sample mean; x' = 76

sample percentage; p = 28% = 0.28

From z-score table online, the z-score with a p-value of 0.28 is approximately;

z = -0.58

Now, the formula for z-score is;

z = (x' - μ)/σ

Plugging in the relevant values, we have;

-0.58 = (76 - 103)/σ

Read more at; brainly.com/question/13523179