Question

2. A grocery store offers a coupon for $2 off when a customer buys 6 or more bottles of water.-The water costs $1.75 per bottle. Shauna uses the function t(b) = 1.75b - 2 to find the total dollars it costs to buy b bottles of water. When she uses the function to find how many bottlesshe can buy for $5, she b finds b ~ 3.4, so she concludes she could buy 3 bottles of water for $5.Explain what error Shauna made

Answer 1

Step-by-step explanation

We are told that the $2 off coupon only applies when you are buying at least 6 bottles. In that case the function that gives the cost in dollars of buying b bottles is in deed the formula found by Shauna:

`t(b)=1.75b-2`

However, as I stated before this formula only applies if you are buying at least 6 bottles. If you buy less you must not count the discount coupon so the equation in that case is:

`t(b)=1.75b`

Shauna found that for 5 dollars b is approximately 3 (which is smaller than 6) which means that she used the wrong equation.

Answer

The error made by Shauna was that she considered the discount coupon on her calculations even though the results tell her that she can buy less than 6 bottles and at that range the coupon can't be used.