1.) You have 12 toppings. You choose one topping--that leaves you with 11 toppings. You choose another--that leaves 10. 12×11×10 = 1,320.
Multiply 1,320 topping choices by 6 cheeses to get 7,920 total combinations.
2.) (Though I'm less sure of these)
CDs: 6×5×4×3×2 = 720
Cassettes: 5×4 = 20
DVDs: 8×7×6×5 = 1680
You are going to get the rate of the detects.
6 detects ÷ 114 light bulbs = 1/19 detects per light bulb
If there are 720 light bulbs, then the number of detects will be
720 light bulbs * 1/19 detects per light bulb = 37. 89 ≈ 38 detects
The answer would be $2.70
