Question

Rameen’s heating bill is $5.42 per month plus $1.08 per therm. How many therms can Rameen use if he wants his heating bill to be a maximum of $87.50? Write the solution in interval notation.

Answer 1

[0,76]

Explanation:

Step 1. Read the problem.

Step 2. Identify what you are looking for.

the number of therms Rameen can buy

Step 3. Name what you are looking for. Choose a variable to represent that quantity.

Let t= the number of therms.

Step 4. Translate. Write a sentence that gives the information to find it. Translate into an inequality.

$5.42 plus $1.08 times the number of therms is less than or equal to $87.50.

5.42+1.08t≤87.50

Step 5. Solve the inequality.

1.08tt≤82.08≤76

Step 6. Check the answer in the problem and make sure it makes sense.

Yes, 5.42+1.08(76)=87.50.

Step 7. Answer the question with a complete sentence.

Rameen can buy no more than 76 therms if he wants his heating bill to be a maximum of $87.50.

Since it is not possible to buy a negative number of therms, the lest number of therms Rameen can buy is 0.

In interval notation, the amount of therms Rameen can buy is [0,76].

Answer 2

Write and solve an inequality:

Total(t) = $5.42 + ($1.08/therm)(t) ≤ $87.50.

First, subtract $5.42 from $87.50: then ($1.08/therm)(t) ≤ $82.08

Next, divide both sides by $1.08 per therm:

t ≤ ($82.08) / ($1.08/therm) = 76 therms (maximum). Thus, Rameen's usage could be [0,76] (therms).