Q3. A fashion corporation group in the US recently launched an online marketing campaign. To evaluate the effectiveness of the campaign, the Marketing Director Max conducted surveys to collect customers' feedbacks from 5 groups of customers of Tim Lok (a fashion brand) and 5 groups of customers of Ka Fai (another fashion brand). Overall, customer evaluation of the campaign is strongly positive. (a) The survey investigated customer satisfaction in four aspects: design, quality, online customer service, and logistics. Each participant needs to indicate their scores between 1 (totally unsatisfied) - 7 (totally satisfied). The answers were recorded and numerically averaged for each group of customers. Answers from customers in Tim Lok were recorded from group 1 to 5, and those from customers in Ka Fai were recorded from group 6 to 10. Max has done a clustering analysis (i.e., hierarchical clustering) based on the collected customer feedbacks and the computer drew a dendrogram (depicting the relative distance between customers' numerical responses of their evaluations) as following.

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