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Jan walks 2 miles at a constant rate of 3 miles per hour and then runs 1 mile at a constant rate of 8 miles per hour.

(a) What is Jan’s average speed for the entire trip?
(b) Is the average speed in part (a) equal to the average of Jan’s two speeds?

Respuesta :

lublana

Answer:

(a).4.36 mph

(b) No

Step-by-step explanation:

We are given that

Jan covered distance,s1 =2 miles

Speed of Jan, a=3 mph

s2=1 mile

b=8mph

a.

We have to find the Jan' s average speed for the entire trip.

Average speed =[tex]\frac{2ab}{a+b}[/tex]

Using the formula

Average speed=[tex]\frac{2(3)(8)}{3+8}=4.36mph[/tex]

b.

Average speed with two speed

Average of Jan’s two speeds

[tex]=\frac{a+b}{2}[/tex]

=[tex]\frac{3+8}{2}=5.5 mph[/tex]

[tex]4.36\neq 5.5[/tex]

Hence, the average speed in part (a) is not equal to the average of Jan’s two speeds.

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