Answer
5
3.5–6.5
Work Step by Step
To find the mean value, first calculate the midpoints of each class as $2,5,8,11,14$,
next multiply each midpoint with its corresponding frequency and add up to get 150,
finally the mean is the ratio of 150 to the total frequency $\mu=150/30=5$
The modal class is the class with the largest frequency. which is 3.5–6.5
