O Levels A Maths Paper 1

SBS 233 X SG

Q3. The value, V dollars, of a house is given by V= V(null) e^kt, where V(null) dollars is the original value of the house when built, t is the time in years since it was built and k is a constant. Calculate

(i) the value of k if, after 10 years, the vaule of the hosue has doubled, [3]
(ii) the vaule of t when the vaule of the house is three times its original value. [2]

Which topic is this under? How to do? Someone explain? Thanks a lot. Wink

Kohler~* SG

hmm. im not sure is my method correct, but tis is wad i wrote for my paper.

since the value V is doubled, so its 2V

V( null ) is the original price, so when V is doubled, V(null) become V0/2

sub this t=10, v=2v, v0= v0/2 and solve the equation...

anyway, actually i dunno how to do tis question at 1st, so just try my luck lo Wink

eagle SG

i) { V() e^10k } / { V() e^0} = 2
Hence, e^10k = 2
10k = ln2
k = 0.1 ln 2

ii) { V() e^kt } / { V() e^0 } = 3
e^kt = 3
kt = ln 3
t = 1/k ln3

tut4nkh4m3n SG

kt meh? if i rmbred right it's -kt

Shocked

eagle SG

methodology still the same

rain-coat SG

yup for e first part 2V(null)=V(null)blahblahblah

then cancel e V(null) get 2=blahblahblah

then e method same for e 2nd part

lpx88 SG

This qn i GG

Actually paper 1 i GG coz damn careless