i agree with whoever it was that nicely quotes the Board of Studies.....i think i was lucky in that i'd done a past paper the night before, and copied the answer about halving the interval method from the back, and learnt it like that....
from the answers from the past paper:
if you halve the interval once..(ive forgotten what the values were from today..and i cant be bothered to lift the laptop off my lap and get up to find the paper...so from what ive read)
(0.7+0.8)/2 = 0.75
then, say g(0.75) >0 and g(0.7) <0 then, from the original two values, the zero is closer to 0.7, thus it is the approximation to the zero to one decimal place
sorry if this was really confusing....but it made sense as i spat it out, lol!