Solving inequalities word problem

Question

A veterinarian tells Max that his cat should lose no more than 30 ounces. The veterinarian suggests that the cat should lose 7 ounces or less per week. What is the shortest time in weeks and days it would take Max’s cat to lose the 30 ounces?

Answer 1

To achieve the total loss, 30 oz, in the shortest number of weeks, assume that the loss is 7 oz per week.

30 = 7w represents total loss in w weeks.

w = 30/7 = 4 & 2/7 so 4 weeks & 2 days of steady loss at the designated rate should do it.

 

This is a sound explanation, but inequalities were not needed.

Answer 2

The cat would lose 7 ounces per week which is 1 ounce per day on average.

Solve 7n=30 where n is the number of weeks. If there is no such n then find the largest n that makes 7n close to 30 (but less than 30).

Then you need to add 1 ounce per day up to 30 ounces.