Suppose that an accounting firm does a study to determine the time needed to complete one person's tax forms. it randomly surveys 175 people. the sample average is 23.3 hours. there is a known population standard deviation of 6.2 hours. the population distribution is assumed to be normal. note: if you are using a student's t-distribution, you may assume that the underlying population is normally distributed. (in general, you must first prove that assumption, though.) construct a 90% confidence interval for the population average time to complete the tax forms

(22.53, 24.07)

Step-by-step explanation:

As per given we have,

n= 175 ,  ,

Critical value for 90% confidence interval :

The population distribution is assumed to be normal.

Since population standard deviation is known , so we use z-test.

Confidence interval :

Hence,  a 90% confidence interval for the population average time to complete the tax forms = (22.53, 24.07)

4a. is 3 miles every hour

4b. is 1/3 of an hour per mile

step-by-step explanation:

b: |12 – x| ≤ 0.25

step-by-step explanation:      

let x be the possible lengths in inches, of the ribbons jaime cut.

we have been given that jaime is cutting strips of ribbon for a project. he tries to cut each piece to be 12 inches long, but sometimes he cuts it too long or too short by as much as 0.25 inch.  

we can represent this information in an inequality as:

by the definition of absolute value function we will get,

upon combining our inequalities we will get,

therefore, the inequality   describes all the possible lengths (x), in inches, of the ribbons jaime cut.

step-by-step explanation: