Geometric sequences question...help!

Even my maths teacher can't do it! Can anyone crack this one?

A mortgage is taken out for £80 000. It is to be paid by annual instalments of £5000 with the first payment being made at the end of the first year that the mortgage was taken out. Interest of 4% is then charged on any outstanding debt. Find the total time taken to pay off the mortgage.

Thanks for your help,
xx

Reply 1

DFranklin

Please read http://www.thestudentroom.co.uk/showthread.php?t=403989, in particular what it has to say about how to ask your questions.

Thanks.

Reply 2

Prokaryotic_crap

well, first year you'll pay £5000+(4% of £80K), second year you'll pay £5000+(4% of £(80K-5K)), third year you'll pay £5000+(4% of £(80k-2(5)K))...

looks long i know, maybe theres an easy way

Reply 3

DFranklin

Prokaryotic_crap

we, first year you'll pay £5000+(4% of £80K), second year you'll pay £5000+(4% of £(80K-5K))...

It's not totally clear what the OP meant, but I can't see any interpretation where the above is correct.

Reply 4

JAKstriked

Oh yeah that question is a bitch.
I sort of managed a solution but it involved a bit of a fiddle adding a couple of years at the end although the decimals were correct. Teacher had no trouble however :\
Look at where DF linked you.