We use that expression " A ballpark figure" to mean an estimate, an approximate number.

我们使用“大致数字”这个表达来表示估计，一个近似数字。

What is the approximate number of students in each class?

【approximate】每个班大致有多少学生？

The profile always shows the approximate number of meals the customer can expect, the size of the meal, how many portions are left and at what time the meal can be picked up, always shortly before closing time.

简介一直显示客户可以预期的大致膳食数量、份量、份数以及收取临期膳食的时间。