Question

A baby weighed $3\frac{2}{5}kg$ at birth two months ago. He gained $2\frac{3}{8}kg$ in two months. How much does the baby weigh now?

Answer 1

The weight of baby at birth is $3\frac{2}{5}kg$

The improper fraction of $3\frac{2}{5}kg$ is

$$\begin{gathered} 3\frac{2}{5} \\ =\frac{3\times 5+2}{5} \\ =\frac{15+2}{5} \\ =\frac{17}{5} \end{gathered}$$

Now, The weight of baby at birth is $\frac{17}{5}kg$

The weight gain by baby after two month is $2\frac{3}{8}kg$

The improper fraction of $2\frac{3}{8}kg$ is

$$\begin{gathered} 2\frac{3}{8} \\ =\frac{2\times 8+3}{8} \\ \frac{=16+3}{8} \\ =\frac{19}{8} \end{gathered}$$

Now, The weight gain by baby after two month is $\frac{19}{8}kg$

To find the Actual weight of baby

Actual weight $=$The weight gain by baby after two month $+$The weight of baby at birth

$$\begin{gathered} =\frac{17}{5}+\frac{19}{8} \\ =\frac{17\times 8}{5\times 8}+\frac{19\times 5}{8\times 5} \\ =\frac{136}{40}+\frac{95}{40} \\ =\frac{136+95}{40} \\ =\frac{231}{40} \end{gathered}$$

Hence, The actual weight of baby now is $\frac{231}{40}kg$