Boy Mow Chau's answer to Audrey's Junior College 1 H1 Maths Singapore question.
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answers for (i) & (ii) shown just for info.
for (iii), treat as linear combination of random variables. note that variances must always be ADDED together.
for (iv), it is a distribution within another distribution.
do check for calculation errors.
for (iii), treat as linear combination of random variables. note that variances must always be ADDED together.
for (iv), it is a distribution within another distribution.
do check for calculation errors.
Date Posted:
2 years ago
Thank you. The answer shows (iii) to be 0.323.
I tried (iii), I also get the same answer as you. Could the answer be wrong?
I tried (iii), I also get the same answer as you. Could the answer be wrong?
Does the answer key show how 0.323 is obtained?
The question gives the mean of male & female as 1.71 & 1.6 respectively, & ...
1.711-1.6 = 0.111
By symmetry of normal distribution ...
P(M-F<0.111) = 0.5
so P(M-F<0.2) must be greater than 0.5 (regardless of what is the variance).
Therefore, even if the answer 0.645 is not right, the answer of 0.323 is unreasonable.
The question gives the mean of male & female as 1.71 & 1.6 respectively, & ...
1.711-1.6 = 0.111
By symmetry of normal distribution ...
P(M-F<0.111) = 0.5
so P(M-F<0.2) must be greater than 0.5 (regardless of what is the variance).
Therefore, even if the answer 0.645 is not right, the answer of 0.323 is unreasonable.
Ok thank you. I think the answer key is incorrect.
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