Statistics · Module 5
Answers and explanations · Reason about probability without losing the denominator
Compare these references after your own attempt. You can read them at any time; they do not record a live model or vendor run.
Statistics · Module 5
Compare these references after your own attempt. You can read them at any time; they do not record a live model or vendor run.
5A. Delayed: 160 flagged, 40 unflagged. Non-delayed: 80 flagged, 720 unflagged. Total flagged=240, so 160/240=66.67% of flags identify delayed jobs. Sensitivity and false-positive rate match the lesson, but the larger base rate raises the positive predictive fraction.
5B. Probability no delivery is late is 0.9³=0.729. At least one late is 1−0.729=0.271, or 27.1%. Multiplication assumes the three outcomes are independent and the per-delivery probabilities are 0.10 under this toy model. Shared conditions could invalidate it.
5C. P(late given priority)=4/20=20%; P(priority given late)=4/28≈14.29%; P(priority and late)=4/100=4%. The first denominator is priority shipments, the second late shipments, and the third all shipments. Reversing a condition changes the question.