Loans/Annuities + subbing numbers (1 Viewer)

[loje]

For questions that ask "how long will it take..." is it valid to simply test some numbers?

For example in 2013 Mathematics 2U paper Q13)d)iii) it asks how long it takes to repay $370k

If I test n = 192, A = $1387.14
and
n = 193, A = -$1603.91

Therefore it will take 193 months to repay.

Will I gain the full 2 marks?

Thanks.

 

[pikachu975]

No because it says:

Finds equation in terms of (1.005)^n or equivalent merit

For one of the marks but you didn't do that.

Also how would you even come up with 192 in the first place? You could be going "50,200,100,150,160,195,170,185,190,191,192,193" which I think solving is faster