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 is a frequency distribution of speeds. Speed (miles per hour) Frequency 45 up to 55 50 55 up to 65 325 65 up to 75 275 75 up to 85 25 picture Click here for the Excel Data File The mean speed of the automobiles traveling on this road is the closest to ____.

Respuesta :

Answer:

The mean speed of the automobiles traveling on this road is the closest to 64 miles per hour

Step-by-step explanation:

Given

[tex]\begin{array}{cc}{Speed} & {Frequency} & {45-55} & {50} & {55-65} & {325} & {65-75} & {275} & {75-85} & {25} \ \end{array}[/tex]

Required

Calculate the mean

First, calculate the midpoint (x)

For 45 - 55: [tex]x = \frac{1}{2}(45+55) = 50[/tex]

For 55 - 65: [tex]x = \frac{1}{2}(55+65) = 60[/tex]

For 65 - 75: [tex]x = \frac{1}{2}(65+75) = 70[/tex]

For 75 - 95: [tex]x = \frac{1}{2}(75+85) = 80[/tex]

So, we have:

[tex]\begin{array}{ccc}{Speed} & {Frequency} & {x} & {45-55} & {50} & {50} & {55-65} & {325} & {60} & {65-75} & {275} &{70} & {75-85} & {25} &{80}\ \end{array}[/tex]

The mean is then calculated as:

[tex]\bar x = \frac{\sum fx}{\sum f}[/tex]

[tex]\bar x = \frac{50*50+325*60+275*70+25*80}{50+325+275+25}[/tex]

[tex]\bar x = \frac{43250}{675}[/tex]

[tex]\bar x = 64.07[/tex]

[tex]\bar x = 64[/tex] --- approximated

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