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# IGCSE maths accuracy Watch

1. V = IR

I and R were measured to 1 decimal place:
I= 4.0
R = 2.7
Find the lower bound for V:

3.95 <= I < 4.05
2.65 <= R < 2.75

3.95x2.65 =10.4675

Now, the paper says on the front: If the answer is not exact, give your answer to 3 significant figures.

I wrote the answer as 10.4675 rather than 10.5. Because I thought 10.5 is not the lowest that V can be, so 10.4675 must be an exact answer?

I'm a little confused as to what they mean by exact?
2. (Original post by SuchBants)
V = IR

I and R were measured to 1 decimal place:
I= 4.0
R = 2.7
Find the lower bound for V:

3.95 <= I < 4.05
2.65 <= R < 2.75

3.95x2.65 =10.4675

Now, the paper says on the front: If the answer is not exact, give your answer to 3 significant figures.

I wrote the answer as 10.4675 rather than 10.5. Because I thought 10.5 is not the lowest that V can be, so 10.4675 must be an exact answer?

I'm a little confused as to what they mean by exact?
You are correct. 10.4675 is the exact answer.

You would lose a mark if you rounded it.
3. (Original post by notnek)
You are correct. 10.4675 is the exact answer.

You would lose a mark if you rounded it.
Thanks wasn't too sure.

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