Question

Margaret can buy 4 jars of honey for 9 dollars and she sells 3 jars of honey for 15 dollars. How many jars of honey would she have to buy to make a profit of 132 dollars?

Answer 1

Hint: We first try to find the cost price of 1 jar of honey using a unitary method. We also use the same process to find the selling price of 1 jar. Then we find the profit for 1 jar using the subtraction method. By dividing the value of 132 with the unitary method we get the number of jars required to profit 132 dollars.

Complete step-by-step solution
Margaret can buy 4 jars of honey for 9 dollars. So, the cost price of 4 jars is 9 dollars.
The cost price of 1 jar will be the division of 9 by 4. The price is $\dfrac{9}{4}$ dollar.
Margaret can sell 3 jars of honey for 15 dollars. So, the selling price of 3 jars is 15 dollars.
The selling price of 1 jar will be the division of 15 by 3. The price is $\dfrac{15}{3}=5$ dollars.
Now we find the profit for 1 jar using the subtraction of cost price from selling price.
Profit is equal to $5-\dfrac{9}{4}=\dfrac{20-9}{4}=\dfrac{11}{4}$ dollars.
She wants to have a profit of 132 dollars.
She got $\dfrac{11}{4}$ dollars profit for 1 jar. We divide 132 by $\dfrac{11}{4}$ to find the number of jars.
Therefore, the number of jars required is $\dfrac{132}{\dfrac{11}{4}}=\dfrac{132\times 4}{11}=12\times 4=48$.

Note: We also can use variables to find the solution. We assume that she has to buy x jars to get profit of 132 dollars. Now she can profit $\dfrac{11}{4}$ dollars profit for 1 jar. So, for x jars the profit will be $\dfrac{11}{4}\times x=\dfrac{11x}{4}$ dollars. So, we equate $\dfrac{11x}{4}=132$ which gives us $x=\dfrac{132\times 4}{11}=12\times 4=48$.