Problema Solution
Sally calculated that she will lose 4.6 calories per minute walking at a rate of 3 miles per hour. How many minutes does she need to walk to burn at least 250 calories? Write and solve an inequality, rounding to the nearest tenth. (Hint: Check your final answer.)
Answer provided by our tutors
Sally's rate of burning calories is c = 4.6 cal/min (on the condition that she is walking at a rate of 3 mph)
let t = the number of minutes she needs to walk to burn at least 250 cal
c = (the number of calories burn)/total time of the walk => the number of calories burnt = total time*c
t*c >= 250
t*4.6 >= 250
by solving the inequality we find
t > 54.3 min
click here to see the step by step solution of the inequality
lets check the answer, indeed
54.3*4.6 = 249.78 cal
54.4*4.6 = 150.24 cal