Answer:
51.3
Step-by-step explanation:
20-30: 100
30-40: 220-100 = 120
40-50: 350-220 = 130
50-60: 750-350 = 400
60-70: 950-750 = 200
70-80: 1000-950 = 50
Mean = sum(f × x) / sum(f)
= [25×100 + 35×120 + 45×130 + 55×400 + 65×200 + 75×50] ÷ 1000
= 51,300 ÷ 1000
= 51.3
