Answer:
the person should walk at least 3.038≈3 miles to burn 200 calories
Step-by-step explanation:
we have 2 contributions
a) reduction of calories by walking
burned calories by walking= calories burning rate * time , but time = distance travelled / velocity , then
burned calories by walking= calories burning rate * distance / velocity
b) increase in calories : snack calories = 90 calories
then
net burned calories = burned calories by walking - increase in calories
net burned calories = calories burning rate * distance / velocity - snack calories
replacing values
net burned calories= 200 cal , calories burning rate= 6.3 cal/minute , velocity = 4 miles /hour *1 hour/60 min = 0.066 miles/minute , snack calories=90 cal , distance = X
then
200 cal = 6.3 cal/min/(0.066 miles/minute) * X - 90 cal
X = (200 cal + 90 cal)* 0.066 miles/minute/6.3 cal/min = 3.038 miles