Question

Bones Brothers & Associates prepare individual tax returns. Over prior years, Bones Brothers has maintained careful records regarding the time to prepare a return. The mean time to prepare a return is 90 minutes, and the population standard deviation of this distribution is 14 minutes. Suppose 100 returns from this year are selected and analyzed regarding the preparation time. What is the probability that the mean time for the sample of 100 returns is between 88 minutes and 92 minutes?

Question 20 options:

	0.1664
	0.8472
	0.8336
	Approximately 1

Answer 1

Solution :

= / n = 14 / 100 = 1.4

= P[(88 - 90) / 1.4 < ( - ) / < (92 - 90) / 1.4)]

= P(-1.43 < Z < 1.43)

= P(Z < 1.43) - P(Z < -1.43)

= 0.9236 - 0.0764

= 0.8472

Probability = 0.8472