Question 1116381
a is correct
b is also correct
c is correct
for d, with continuous
7000=3500e^(0.0265t)
2=e^(0.0265t)
ln2=0.0265t
0.693=0.0265t
t=26.25 years
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for d, with 3.2 per cent
2=1.032^t
ln both sides
ln 2=t ln (1.032)
divide both sides by ln (1.032)
t=22.0 years
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for d, with an increase of 80 per year
doubles after 3500/80=43.75 years