The tread life of a particular brand of tire is a random variable best described by a normal distribution with a mean of 60,000 miles and a standard deviation of 8,300 miles. What proportion of these tires last between 40,000 and 45,000 miles

P [ 40000 ≤ X ≤ 45000 ] =  0,02773    or  2,8 %

Step-by-step explanation:

P [ 40000 ≤ X ≤ 45000 ]  = ?

To find the probablity    P [ X ≤ 40000 ] =  ?

z(s)  = ( X - x ) / σ

z(s)= ( 40000 - 6000 )/ 8300

z(s) =  -20000/8300

z(s) ≈  - 2,41

Then

from z-table we find P [ X ≤ 40000] =  0,00820

Now again:

For  P [ X ≤ 45000 ]

z₂  = ( X - x ) / σ

z₂ =  ( 45000 - 6000 ) / 8300

z₂ = - 15000 / 8300

z₂ = - 1,8072

z₂ ≈ 1,81

From z - table

For  P [ X ≤ 45000 ] =   0,03593

Then:

P [ 40000 ≤ X ≤ 45000 ] = 0,03593 - 0,00820

P [ 40000 ≤ X ≤ 45000 ] =  0,02773    or  2,8 %

d

step-by-step explanation:

the 2000 florida legislature amended section 322.05, florida statutes, changing the requirements to obtain a class e license for a driver under the age of 18 holding a learner's license. the following requirements must be met in order to obtain a regular class e license if a learner's license is issued on or after october 1, 2000:

must hold a learner's license for at least 12 months or until the 18th birthday.

must have no convictions 12 months from the issue date of the learner's license.

may have one traffic conviction within 12 months from the issue date of the learner's license if adjudication is withheld.

a parent, legal guardian, or responsible adult over 21 years old must certify that the driver has 50 hours driving experience, including 10 hours of night time driving.