{"blocks": [{"key": "d27c18da", "text": "Scenario", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "59bf4cd8", "text": "Email marketing team wants to evaluate the performance of a new subject line.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "23883736", "text": "Question", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "e8d48c51", "text": "Define the null and alternative hypotheses for comparing click-through rates between control and test emails. Explain how the Central Limit Theorem justifies using a z-test in large samples. Derive the sample size needed to detect a 2-percentage-point lift with 80% power at α = 0.05.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "548b60a3", "text": "Hints", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "2d25a4c7", "text": "Think proportions, pooled variance, power formula.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}], "entityMap": {}}