2011 A-level H2 Mathematics (9740) Paper 2 Question 5 Suggested Solutions

All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.

$X \sim \mathrm{N}(\mu, \sigma^2)$

$\mathrm{P}(X \textless 40.0) = 0.05$

$\Rightarrow \frac{40 - \mu}{\sigma} = -1.6449 \rightarrow (1)$

$\mathrm{P}(X \textless 70.0) = 0.05$

$\Rightarrow \frac{70 - \mu}{\sigma} = 1.9600 \rightarrow (1)$

Solving, $\mu = 53.7$ and $\sigma = 8.32$

KS Comments:

A very straightforward question here, as it didn’t even try to trick unsuspecting students who often forget to change the signs before applying inverse norm function. Please use a Graphing Calculator to solve if you aren’t good with simultaneous equations.

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KS Teng

KS has been teaching H2/H1 Mathematics and IB mathematics for the more than 10 years. Having taught students from all various Junior Colleges, KS adapts to students' abilities and help them better understand the topics. As someone who loves to teach mathematics and sees it as a truly useful tool in life, KS seeks to enable students to appreciate math. Therefore, his tuition mission is to motivate and cultivate students to be independent and confident thinkers.

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2011 A-level H2 Mathematics (9740) Paper 2 Question 5 Suggested Solutions

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