SPM 2020 Add Maths Paper 1, Question 20Progressions

Solved on video in English and Bahasa Melayu · 4 marks · Form 4, Progressions · 5:31 video

The question

Adam invested RM100 000 as initial investment on 1 June 2007 with a fixed return rate. Table 1 shows the total amount of money for the next three consecutive years: 1 June 2008 = RM108 000.00; 1 June 2009 = RM116 640.00; 1 June 2010 = RM125 971.20. Due to the economic recession, there was no return on investment for the year 2011 and the year 2012. For the year 2013 onwards, the fixed return rate resumes as previously. Adam intends to buy one of the houses shown in Diagram 10 by cash using all of his investment money earned on 1 June 2020. House Type A: original price RM250 000, discount 5%. House Type B: original price RM270 000, discount 15%. Determine the type of house that Adam can afford to buy by only using his investment money. Hence, calculate his remaining investment money after buying the house.

[4 marks]

SPM 2020 Add Maths Paper 1, Question 20: the question as drawn in Eduly's video5:31

Step 1

The yearly amounts form a GP. Fixed return rate r = 108 000/100 000 = 1.08.

Why this step

Each year's amount is last year's times the same 1.08. A constant multiplier means a GP, which tells us which formula to use.

6 more steps, each with the reason for it, in the full solution

Final answer

Type B; remaining money = RM3 663.90

Where students lose marks

Watch out: the 2020 amount is one term, T_n, not a sum. Using S_n gives the right house but wrong remaining money.

Watch every step of this question solved on video (5:31), with the reason behind each step and a box that checks your own answer.

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