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# Help needed for an S2 question watch

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1. Hi
In january 2003, there was the first qustion on the uniform distribution. But I'm not sure how to do the last 2 parts. Can someone please explain how to do them? The question is:
An engineer measures to the nearest cm, the lengths of metal rods.
b) Find the probability that for a randomly chosen rod, the measured length will be well within 0.2cm of their true lengths.

Two rods are chosen at random
c) Find the probability that for both rods, the measured lengths will be within 0.2cm of their true lengths.
2. Originally posted by Xenon
Hi
In january 2003, there was the first qustion on the uniform distribution. But I'm not sure how to do the last 2 parts. Can someone please explain how to do them? The question is:
An engineer measures to the nearest cm, the lengths of metal rods.
b) Find the probability that for a randomly chosen rod, the measured length will be well within 0.2cm of their true lengths.

Two rods are chosen at random
c) Find the probability that for both rods, the measured lengths will be within 0.2cm of their true lengths.
I think the question may be in complete, but if you take the accuracy of measurement to be to +/- 0.5cm then the probability that they will be within 0.2cm is 0.4 (taking the area under the graph from +0.2 to -0.2).

c) can be done using a binomial distribution;

P(X=2) where N=2 and P=0.4
3. part c is 0.4 ^2 = 0.16. Use a tree diagram. Not binomial

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