Submit Quiz Quiz: Bonus Quiz This Question: 4 pts 5016(4 complete) This Quiz: 25
ID: 3062142 • Letter: S
Question
Submit Quiz Quiz: Bonus Quiz This Question: 4 pts 5016(4 complete) This Quiz: 25 pts possible According to a marketing website, adults in a certain country average 56 minutes per day on mobile devices this year. Assume that minutes per day on mobile devices follow the normall distribution and has a standard deviation of 9 minutes. Complete parts a through d below a. What is the probability that the amount of time spent today on mobile devices by an adult is less than 58 minutes? (Round to four decimal places as needed.) b. What is the probability that the amount of time spent today on mobile devices by an adult is more than 50 minutes? (Round to four decimal places as needed.) e. What is the probability that the amount of time spent today on mobile devices by an adult is between 40 and 53 minutes? (Round to four decimal places as needed.) d. What amount of time spent today on mobile devices by an adult represents the 85th percentile? Anamount of time ofminutes represents the 85th percentile. Round to two decimal places as needed.) Enter your answer in each of the answer boxes.Explanation / Answer
a) P(X < 58)
= P(z < (58 - 56)/9)
= P(z < 0.22)
= 0.5879
b) P(X > 50)
= P(z > (50 - 56)/9)
= P(z > -0.67)
= 0.7475
c) P(40 < X < 53) = 0.3317
d) z score for 85th percentile = 1.04
Hence,
X = 56 + 1.04*9
X = 65.36 minutes