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# AQA D1 Algorithm-'two reasons why the algorithm is unsatisfactory in its present form Watch

1. I'm stuck on the following question part b:

I got one reason down since the algorithm doesn't give a specific output, it doesn't have a line which tells you to print the number. However for the second reason it talks about the cube root being in an interval like this:
'Need to know an interval within which the cube root lies at the outset'

'Many identified the lack of output but most struggled to identify the need for an interval to be known and those who did often lacked the ability to express themselves clearly'

The algorithm finds an approximate cube root, I don't know what it means by an interval, what interval is it talking about? I didn't know there was an interval when finding a cube root, can anyone explain?

Here's the mark scheme for reference with the cube root underlined:
2. (Original post by Sayless)
I'm stuck on the following question part b:
An interval on the number line. In this case the algorithm assumes the cube root lies between 6 and 7 (A and B), i.e in the inteval [6,7]

It is essentially doing a binary chop on the interval, zeroing in on the cube root.
3. (Original post by ghostwalker)
An interval on the number line. In this case the algorithm assumes the cube root lies between 6 and 7 (A and B), i.e in the inteval [6,7]

It is essentially doing a binary chop on the interval, zeroing in on the cube root.
Ah I didn't even question the numbers being used, I should have looked at everything, great explanation thank you.

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