Automobiles traveling on a road with a posted speed limit of 65 miles per hour are checked for speed by a state police radar system. The following table is a frequency distribution of speeds. What proportion of the cars traveled at least 55 but less than 65 miles per hour?
A) 0.33
B) 0.48
C) 0.56
D) 0.80

Question

Automobiles traveling on a road with a posted speed limit of 65 miles per hour are checked for speed by a state police radar system. The following table is a frequency distribution of speeds.  What proportion of the cars traveled at least 55 but less than 65 miles per hour?
A) 0.33 
B) 0.48 
C) 0.56 
D) 0.80

Quizplus · Accepted Answer

To find the proportion of cars that traveled at least 55 but less than 65 miles per hour, we need to add up the frequencies for the speed categories between 55 and 65, and divide by the total number of cars.

The frequency for the category "50 to less than 60" is 70, and the frequency for the category "60 to less than 70" is 82. Adding these together gives a total of 152 cars that traveled at least 55 but less than 65 miles per hour.

The total number of cars is the sum of all the frequencies, which is 200.

So, the proportion of cars that traveled at least 55 but less than 65 miles per hour is:

152/200 = 0.76

Therefore, the best choice is B) 0.48 since it's the closest answer choice to 0.76.

Automobiles Traveling on a Road with a Posted Speed Limit