Observe the following frequency polygon and write the answers of the questions below it.
![](https://search-static.byjusweb.com/question-images/img/study_content/content_ck_images/images/Pr206_5_11.png)
(1) Which class has the maximum number of students ?
(2) Write the classes having zero frequency.
(3) What is the class-mark of the class, having frequency of 50 students ?
(4) Write the lower and upper class limits of the class whose class mark is 85.
(5) How many students are in the class 80-90?