Answer:
30.5
0<h<10 =5
10<h<20 =15
20<h<30 =25
30<h<40 =35
40<h<50 =45
50<h<60 =55
multiply by frequency
5*1=5
15*4=60
25*7=175
35*2=70
45*3=135
55*3=165
add
=610
610 divided by 20 =30.5
