business maths q?

[xoxogossipgirl]

so, to get the answer for the MC question on inflation below (MAV 2009) you had to:
figure out the $ increase over the 8 years ($1.75), divide it by the original amount ($0.90) and times that by 100. then to get the annual inflation rate, you had to divide that amount (194.44%) by 8, which was 24.31%

however i tried to apply the same principal to the attached SA q (MAV 2008)
and got 5.04% - which was incorrect, and it was actually 3.89%. in their solutions they just used the normal compound interest formula

i might be missing something really obvious, but i just don't see the difference in these 2 questions that mean using a complete different method.
i know there must be something obvious i'm not seeing,
so if anyone could point it out to me that'd be amazing
thank you

[plato]

I get the answer to the first question as 14.45% and not 24.31%
The simplest way is to use the TVM Solver with PMT = -0.9 and FV = +2.65
Check: 

Using the same method in the second question gives me 3.8886%
Check: 

[xoxogossipgirl]

MAV's solutions say D, 24.31% =X
It was in my cheatbook coz I know that when I did it first (probably using compound interest formula) I got 14.45%

Safer to assume the compound interest way and assume it's a bloody company exam mistake?
I might go ask my teacher before the exam tomorrow =/