Question

Melissa walks 3 miles to the house of a friend and returns home on a bike. She averages 4 miles per hour faster when cycling than when walking, and the total time for both trips is two hours. Find her walking speed (HINT: Write an expression that represents the time it takes for Melissa to walk to her friends house, and then write an expression for the time it takes to cycle back. The sum of these expressions is equal to the total time of the trip.)

Answer 1

walking speed is 2 m/s

Explanation:

given data

distance between Melissa and friend = 3 mile

total time of the trip = 2 hour

solution

we consider here

walking speed = s₁

bike speed = s₂

so s₂ = s₁ + 4 .................1

and

time is express as

time = distance ÷ speed .................2

so time for Melissa to friend reach = 3 ÷ s₁

and time for return from her friend = 3 ÷ s₂

so put this value in equation 2 we get

time = 3 ÷ s₁ + 3 ÷ s₂

2 =
`(3)/(s_1) + (3)/(s_1 + 4)`

solve it and we will get

s₁² + s₁ - 6 = 0

s₁ = 2 m/s

so walking speed is 2 m/s