Question

At 1:30 Marlon left his house to go to the beach, a distance of 7.2 miles. He rode his skateboard until 2:15, then walked the rest of the way. He arrived at the beach at 3:00. Marlon's speed on his skateboard is 2 times his walking speed. Find his speed when walking and when skateboarding

Answer 1

Answer:  The speed when walking = 3.2 miles per hour

The speed when skateboarding=2(3.2)=6.4 miles per hour

Step-by-step explanation:

Let x be the walking speed then his speed on skateboard be 2x.

Time taken in skateboarding = 1:30-2:15= 45 minutes=3/4 hour

Distance traveled by skating is given by :-

$d_1=speed*time=2x(\frac{3}{4})=\frac{3}{2}x$

Time taken for walking = 2:15-3:00=45 minutes=3/4 hour

Distance traveled by walking is given by :-

$d_2=speed*time=\frac{3}{4}x$

Distance between house and beach = 7.2 miles

$\\\Rightarrow\ d_1+d_2=7.2\\\Rightarrow\ \frac{3}{2}x+\frac{3}{4}x=7.2\\\\\Rightarrow\ \frac{9}{4}=7.2\\\Rightarrow\ x=\frac{7.2\times4}{9}\\\Rightarrow\ x=3.2$

Hence, The speed when walking = 3.2 miles per hour

The speed when skateboarding=2(3.2)=6.4 miles per hour