Probability & Statistics 2 — Variant 2

A Level Mathematics · 9709/62 · Oct/Nov 2022

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Questions

3 of 7 questions shown here, checked against the paper. The others are in the PDF above — they contain diagrams or maths we could not yet verify, and we would rather show you the original than a transcription we are not sure of.

3
1.6%1.6\% of adults in a certain town ride a bicycle. A random sample of 200200 adults from this town is selected.
3(a) [4]
Use a suitable approximating distribution to find the probability that more than 33 of these adults ride a bicycle.
3(b) [2]
Justify your approximating distribution.
5
XX is a random variable with distribution B(10,0.2)\mathrm{B}(10, 0.2). A random sample of 160160 values of XX is taken.
5(a) [3]
Find the approximate distribution of the sample mean, including the values of the parameters.
5(b) [3]
Hence find the probability that the sample mean is less than 1.81.8.
6
The masses, in grams, of small and large bags of flour have the distributions N(510,100)\mathrm{N}(510, 100) and N(1015,324)\mathrm{N}(1015, 324) respectively. André selects 44 small bags of flour and 22 large bags of flour at random.
6(a) [5]
Find the probability that the total mass of these 66 bags of flour is less than 41304130 g.
6(b) [5]
Find the probability that the total mass of the 44 small bags is more than the total mass of the 22 large bags.

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