Histogram 适合连续型数据。这里的工作时间是连续变量，所以可以用 histogram 表示。

Time worked is continuous, so a histogram is suitable.

先用 $10$ 到 $20$ 小时这一组的频数 $16$ 定出纵轴比例。然后从图上读出相应的频率密度，用面积表示频数。

题目要求 $12$ 到 $24$，它横跨 $10$ 到 $20$ 以及 $20$ 到 $25$ 两组，所以要分两段算面积。

For the interval $10$ to $20$ hours,

Since the class width is $10$, the frequency density is

From the histogram, the frequency in the interval $20$ to $25$ hours is $14$.

Therefore the estimated number between $12$ and $24$ hours is

一共有 $64$ 人，所以中位数位置取第 $32$ 个数据。由 histogram 的面积可知，到 $20$ 小时累计 $21$ 人，到 $25$ 小时累计 $35$ 人，所以第 $32$ 个在 $20$ 到 $25$ 这一组内。

在这一组内做线性插值。

The median is the $32$nd value.

From the histogram, the cumulative frequency up to $20$ hours is $21$, and the cumulative frequency up to $25$ hours is $35$.

So the median lies in the interval $20$ to $25$ hours.

Using linear interpolation,

So the estimated median is

to $1$ decimal place.

正态分布是对称的，因此平均数和中位数应当接近。Charlie 的平均数是 $23.9$，上一小题估计的中位数也是约 $23.9$，所以这个决定是合理的。

Charlie’s decision is reasonable.

The estimated mean is $23.9$ hours and the estimated median is approximately $23.9$ hours. Since these are approximately equal, the data are consistent with a normal distribution.