Question

Mario makes a cake weighing $4\frac{1}{2}$ pounds. He decides to make similar cakes for 4 of his friends. Which of the following equations would help find the total weight of the cakes he made for himself and his friends?

• A. Division equation: $\frac{9}{2}÷4=\frac{9}{8}$
• B. Multiplication equation: $\frac{9}{2}\times 5=\frac{45}{2}$
• C. Multiplication equation: $\frac{9}{2}\times 4=\frac{36}{2}$
• D. Division equation: $\frac{9}{2}÷\frac{9}{10}=5$

Answer 1

The correct option is B Multiplication equation: $\frac{9}{2}\times 5=\frac{45}{2}$

Weight of each cake $=4\frac{1}{2}lb=\frac{4\times 2+1}{2}=\frac{9}{2}$
Number of people = Mario + 4 of his friends = 5

Total weight of the cakes = weight of each cake × number of people
$=\frac{9}{5}\times 5=\frac{9\times 5}{2\times 1}=\frac{45}{2}lb$

Multiplication equation: $\frac{9}{2}\times 5=\frac{45}{2}\text{or}5\times \frac{9}{2}=\frac{45}{2}$

Division equation: $\frac{45}{2}÷5=\frac{9}{2}\text{or}\frac{45}{2}÷\frac{9}{2}=5$

Hence, option C is correct.