Question

estimate the sum using benchmarks.
\\(\frac{1}{5} + \frac{3}{8}\\)
\\(\frac{1}{2}\\)
1
\\(1\frac{1}{2}\\)

Explanation:

Step1: 估算每个分数的基准值

$\frac{1}{5}=0.2$，接近0；$\frac{3}{8}=0.375$，接近$\frac{1}{2}$

Step2: 计算基准值的和

$0 + \frac{1}{2} = \frac{1}{2}$，实际计算$\frac{1}{5}+\frac{3}{8}=\frac{8}{40}+\frac{15}{40}=\frac{23}{40}=0.575$，接近$\frac{1}{2}$

Answer:

$\boldsymbol{\frac{1}{2}}$