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2 Statistics

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Question 395

The yield of a specific chemical reaction, YYY grams, is modeled by a normal distribution such that Y∼N(120,152)Y \sim \text{N}(120, 15^2)Y∼N(120,152).

a.

Determine the probability that a randomly selected batch results in a yield of less than 138 g.

[2]
b.

Calculate the upper quartile, Q3Q_3Q3​, of the yield YYY.

[2]
c.

Using the symmetry of the distribution, write down the lower quartile, Q1Q_1Q1​, of YYY.

[1]
d.

An outlier in this process is defined as any yield YYY such that Y<hY < hY<h or Y>kY > kY>k, where

h=Q1−1.5×(Q3−Q1)andk=Q3+1.5×(Q3−Q1) h = Q_1 - 1.5 \times (Q_3 - Q_1) \quad \text{and} \quad k = Q_3 + 1.5 \times (Q_3 - Q_1) h=Q1​−1.5×(Q3​−Q1​)andk=Q3​+1.5×(Q3​−Q1​)

Calculate the value of hhh and the value of kkk.

[2]
e.

Find the probability that a randomly selected batch yield is classified as an outlier.

[2]
Markscheme

2 Statistics Questions

  1. A Level
  2. /Maths
  3. /2 Statistics

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