Answer:
Sam average speed for the whole journey = [tex]3\frac{3}{11} mph[/tex]
Step-by-step explanation:
Formula: Speed = [tex]\frac{Distance}{Time}[/tex]
i.e. Time = [tex]\frac{Distance}{Speed}[/tex]
If Sam walked x miles at 4 mph, then time taken by him = [tex]\frac{x}{4}[/tex] hours
If he then walked 2x miles at 3 mph, then time for this period = [tex]\frac{2x}{3}[/tex]hours
Average speed = [tex]\frac{Total Distance}{Total Time}[/tex]
=[tex]\frac{x+2x}{\frac{x}{4} \frac{2x}{3} }[/tex]
=[tex]\frac{3x}{\frac{x1}{4} \frac{2}{3} }[/tex]
=[tex]\frac{3}{\frac{3+8}{12} }[/tex]
=[tex]\frac{3 x 12}{11}[/tex]
=[tex]\frac{36}{11}[/tex]
=[tex]3\frac{3}{11} mph[/tex]
Hence, Same's average speed for the whole journey = [tex]3\frac{3}{11} mph[/tex]
