Average speed on a freeway is 76 mph. Ten percent (10%) ofvehicles is drive 12 m

Question

Average speed on a freeway is 76 mph. Ten percent (10%) ofvehicles is drive 12 miles above the speed limit of 70 miles per hour. 32 What fraction of vehicles drive below the speed limit? 0.1841 0.1357 0.1003 0.0885 33 what fraction drive within ±5 mph from the mean? 0.6262 0.6626 0.7154 0.7546 34 what fraction drive within ±1.5 standard deviations from the mean? 0.8219 0.8664 0.8856 0.9032 35 mph. (Round The middle interval within which 90% ofvehicles drive is your answers to the nearest integer.) 70.0 68.3 66.8 65.1 82.0 83.7 85.2 86.9

Explanation / Answer

for top 10% ; zscore =1.28

hence std deviation =(X-mean)/std deviation =(82-76)/1.28 =4.682

32)

option C

33)

option C

34)

option B

35)

formiddle 90% values ; z=1.645

hence values =mean -/+ z*std deviation =68.3 to 83.7

option B

for normal distribution z score =(X-)/ here mean=       = 76.000 std deviation   == 4.682

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