Part 1: P(Churn = Yes)

1,869/7043= 26.5%

Part 2.1: P (Churn = Yes | SeniorCitizen = 1)

476/1142= 41.7%

Part 2.2: P (SeniorCitizen = 1 AND Churn = Yes)

476/7043 =6.8%

Part 2.3: P (Fiber optic OR PaperlessBilling)

P (A) - 3096/7043 = 44.0%

P (B) - 4171/7043 = 59.2%

P (A and B) - 2395/7043 = 34.0%

Final Probability - 44.0% + 59.2% - 34.0% = 69.2%

Part 2.4: P (PaymentMethod = Electronic check | Contract = Two year)

168/1695 = 9.9%

Chapter 4

Chapter 5

1.

Mean: 64.762

Std. Deviation: 30.09

2.

Lower Bound: 64.762 - (2 * 30.09) = 4.582

Upper Bound: 64.762 + (2 * 30.09) = 124.942

4.

7043/7043 = 100% of customers falling into this range