The upper limit of a class-interval is called class-mark.
Fill in the blanks : (i) Lower class limit of 15-18 is ___ . (ii) Upper class limit of 24-30 is ___. (iii) Upper limit of 5-12.5 is ___. (iv) If the upper and the lower limits of a class interval are 16 and 10; the class interval is ___. (v) If the lower and the upper limits of a class interval are 7.5 and 12.5; the class interval is ___.
Class mark of a certain class interval is 30 and its lower class limit is 20. Then its upper class limit is