Y9 Booklet 14 – Interest and Geometric Sequences | Original 12-page PDF

Exact unchanged original Y9 Booklet 14 – Interest and Geometric Sequences | Original 12-page PDF.

Keep the original page, question and subpart numbers when following the matching lesson recordings. Each recording may cover selected examples; the complete PDF includes additional practice. This is the original teaching booklet, with its original historical labels and layout.

Spiral learning connection: connect these skills to earlier number, algebra and modelling ideas, then return to them in later problems.

Original-edition clarifications (the PDF itself is unchanged):

• Page 5, Q8(f): using the stated 360-day year and the fractional compound-interest model, t = log(5001/5000)/log(1.04) years ≈ 1 day, 20 hours, 3 minutes, 14.21 seconds. The printed 1 day, 20 hours, 9 minutes, 36 seconds is incorrect.

• Recording clarification for page 10, Q12: Bank A compounds the entire first-year balance, so its value after three years is 3000 × 1.025 × 1.015² = $3167.94, rather than the recorded $3165.68. Bank B uses simple interest: 3000(1 + 0.016 × 3) = $3144. For t years after investment (t ≥ 1), use A(t) = 3075 × 1.015⁽ᵗ⁻¹⁾ and B(t) = 3000(1 + 0.016t). The first complete years reaching $3500 are year 10 for A and year 11 for B; the first-year interest must compound in A’s later years.

• Pages 11–12 retain original handwritten sequence notes and practice. Some worked rules are left for completion; the file is not a complete worked-solutions edition. The original historical question data and rates are unchanged.