Suppose only 75% of all drivers in a certain state regularly wear a seat belt. a random sample of 500 drivers is selected. what is the probability that a. between 360 and 400 (inclusive) of the drivers in the sample regularly wear a seat belt? b. fewer than 400 of those in the sample regularly wear a seat belt? devore, jay l.. probability and statistics for engineering and the sciences (p. 169). cengage learning. kindle edition.

a.   0.93449

b. 0.99506

Step-by-step explanation:

Given : The proportion of all drivers in a certain state regularly wear a seat belt : p=0.75

Sample size : n=500

Let x be the random variable that represents the number of drivers in a certain state regularly wear a seat belt.

Then ,

a.  The probability that between 360 and 400 (inclusive) of the drivers in the sample regularly wear a seat belt :

∴ The probability that between 360 and 400 (inclusive) of the drivers in the sample regularly wear a seat belt= 0.93449

b. The probability that fewer than 400 of those in the sample regularly wear a seat belt :-

∴ The probability that fewer than 400 of those in the sample regularly wear a seat belt = 0.99506

walter needs to make at least 5 more cookies but no more than 40. 5 ≤ x ≤ 40

step-by-step explanation:

20 ≤ x + 15 ≤ 55

subtract 15 from all parts

20-15 ≤ x + 15-15 ≤ 55-15

5 ≤ x ≤ 40

this means how many more cookies he has to make

walter needs to make at least 5 more cookies, but no more than 40 cookies; 5 ≤ x ≤ 40

29933333.33

step-by-step explanation: