(Ch.4, Q.6) need answer for first blank, I got 69% which is wrong, correct answe

Question

(Ch.4, Q.6) need answer for first blank, I got 69% which is wrong, correct answer for 2nd blank is 16%
In a study investigating the effect of car speed on accident severity, 5000 reports of fatal automobile accidents were examined, and the vehicle speed at impact was recorded for each one. For these 5000 accidents, the average speed was 41 mph and that the standard deviation was 14 mph. A histogram revealed that the vehicle speed at impact distribution was approximately normal. (a) Roughly what proportion of vehicle speeds were between 27 and 55 mph? (Round the answer to the nearest whole number.) Approximately %?
(b) Roughly what proportion of vehicle speeds exceeded 55 mph? (Round the answer to the nearest whole number.) Approximately 16%


(Ch.4, Q.6) need answer for first blank, I got 69% which is wrong, correct answer for 2nd blank is 16%
In a study investigating the effect of car speed on accident severity, 5000 reports of fatal automobile accidents were examined, and the vehicle speed at impact was recorded for each one. For these 5000 accidents, the average speed was 41 mph and that the standard deviation was 14 mph. A histogram revealed that the vehicle speed at impact distribution was approximately normal. (a) Roughly what proportion of vehicle speeds were between 27 and 55 mph? (Round the answer to the nearest whole number.) Approximately %?
(b) Roughly what proportion of vehicle speeds exceeded 55 mph? (Round the answer to the nearest whole number.) Approximately 16%



In a study investigating the effect of car speed on accident severity, 5000 reports of fatal automobile accidents were examined, and the vehicle speed at impact was recorded for each one. For these 5000 accidents, the average speed was 41 mph and that the standard deviation was 14 mph. A histogram revealed that the vehicle speed at impact distribution was approximately normal. (a) Roughly what proportion of vehicle speeds were between 27 and 55 mph? (Round the answer to the nearest whole number.) Approximately %?
(b) Roughly what proportion of vehicle speeds exceeded 55 mph? (Round the answer to the nearest whole number.) Approximately 16%


In a study investigating the effect of car speed on accident severity, 5000 reports of fatal automobile accidents were examined, and the vehicle speed at impact was recorded for each one. For these 5000 accidents, the average speed was 41 mph and that the standard deviation was 14 mph. A histogram revealed that the vehicle speed at impact distribution was approximately normal. (a) Roughly what proportion of vehicle speeds were between 27 and 55 mph? (Round the answer to the nearest whole number.) Approximately %?
(b) Roughly what proportion of vehicle speeds exceeded 55 mph? (Round the answer to the nearest whole number.) Approximately 16% In a study investigating the effect of car speed on accident severity, 5000 reports of fatal automobile accidents were examined, and the vehicle speed at impact was recorded for each one. For these 5000 accidents, the average speed was 41 mph and that the standard deviation was 14 mph. A histogram revealed that the vehicle speed at impact distribution was approximately normal. (a) Roughly what proportion of vehicle speeds were between 27 and 55 mph? (Round the answer to the nearest whole number.) Approximately %?
(b) Roughly what proportion of vehicle speeds exceeded 55 mph? (Round the answer to the nearest whole number.) Approximately 16%

Explanation / Answer

Here it is given that its normal distribution with mean=41 and sd=14

a. P(27<x<55)=P(27-41/14<z<55-41/14)=P(-1<z<1)=68.27%=68%

b. P(x>55)=P(z>1)=15.87%=16%

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