8.5.2 Верно!!!

import pandas
import seaborn

data = pandas.read_csv('support_data.csv')

segments_old = ['Segment 0', 'Segment 1', 'Segment 2']
segments_new = ['Потенциальные клиенты', 'Обычные клиенты', 'VIP-клиенты']
intervals = ['До внедрения роботов', 'После внедрения роботов']

intervals_column = list(data['interval'])
segments_column = list(data['segment'])
duration_column = list(data['duration'])
#print(duration_column[:10])
mean_duration = []

# ваш код здесь
for segment in segments_old:
    interval_duration = []
    # вложенный цикл по двум периодам
    for interval in intervals:
        score = 0
        counter = 0
        # вложенный цикл по строкам
        for index in range(len(data)):
            if (segments_column[index] == segment and
                intervals_column[index] == interval):
                score += duration_column[index]
                counter += 1
        print(score, counter)
        interval_duration.append(score / counter)
    print(interval_duration)
    mean_duration.append(interval_duration)

seaborn.heatmap(mean_duration, xticklabels=intervals, yticklabels=segments_new, annot=True, cmap='RdYlGn')