Mixed practice: which model? Problem set B Answers

1. (a) Arithmetic (\(d = -3.5\))
2. (b) Geometric (\(r = 1.25\))
3. (c) Neither
4. (d) Geometric (\(r = -\frac{1}{2}\))

\(n = 11\) (\(u_{11} = 68,\ v_{11} \approx 74.5\))

\(4500 + 7 \times 144 = 5508\), so €5508.

Month 18 (A: $910, B: $916.81)

\(d = \dfrac{10.0 - 4.0}{4} = 1.5\); \(u_{12} = 4 + 11(1.5) = 20.5\) kg.

(a) A term: \(12 + 17(3) = 63\). (b) A sum: \(\frac{18}{2}(12 + 63) = 675\).

(a) Geometric, r = 2 (b) 768 (c) 1533