If the mileage per gallon for a car is normally distributed, 32 mpg has a z score of 1.2, and 24 mpg, has a z score of -.4, what is the mean mpg of the distribution?

Respuesta :

Answer:

  26 mpg

Step-by-step explanation:

The given numbers let you write two equations using the relation ...

  z = (x - μ)/σ

Filling in the numbers, we have ...

  1.2 = (32 - μ)/σ

  -0.4 = (24 - μ)/σ

Dividing the first equation by the second gives ...

  -3 = (32 -μ)/(24 -μ)

  -3(24 -μ) = 32 -μ . . . . . multiply by the denominator

  -72 +3μ = 32 -μ . . . . . eliminate parentheses

  4μ = 104 . . . . . . . . . . . . add 72+μ

  μ = 26 . . . . . . . . . . . . . . divide by 4

The mean of the distribution was 26 mpg.

The mean of the distribution of the mileage per gallon for the car is 26

The given parameters are:

  1. 32 mpg has a z score of 1.2
  2. 24 mpg, has a z score of -.4,

The z-score of a distribution is:

[tex]z = \frac{x - \bar x}{\sigma}[/tex]

So, we have the following equations

[tex]1.2 = \frac{32 - \bar x}{\sigma}[/tex]

and

[tex]-4 = \frac{24 - \bar x}{\sigma}[/tex]

Divide both equations

[tex]-3 = \frac{32 - \bar x}{24- \bar x}[/tex]

Cross multiply

[tex]-72 + 3\bar x = 32 - \bar x[/tex]

Collect like terms

[tex]\bar x + 3\bar x = 32 + 72[/tex]

[tex]4\bar x = 104[/tex]

Divide both sides by 4

[tex]\bar x = 26[/tex]

Hence, the mean of the distribution is 26

Read more about normal distribution at:

https://brainly.com/question/4079902