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junior college 2 | H2 Maths
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Candice lim
Candice Lim

junior college 2 chevron_right H2 Maths chevron_right Singapore

Hi, I am stuck at part (a) (ii), just can't solve it. Pls help. Thank you very much!

Date Posted: 1 year ago
Views: 431

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Boy Mow Chau
Boy Mow Chau's answer
317 answers (Tutor Details)
1st
for (a)(ii), the order of drawing out the 4 matched & 4 unmatched numbers from the box, does not affect the win, so we need to multiply the probability by the ways to rearrange 4 identical objects of type "matched" & 4 identical objects of type "unmatched" amongst 8 objects.

for (b), it is a GP, so just use sum of GP formula.
Candice lim
Candice Lim
1 year ago
Thank you so much Mr Chau!

Hope you have a great day ahead :)
Candice lim
Candice Lim
1 year ago
Hi Mr Chau, may I know why the calculation for probability of selecting 4 matched numbers starts with 7/45 and not 8/45? Kindly advise, thank you so much!
Boy Mow Chau
Boy Mow Chau
1 year ago
you should consider the number of winning numbers, not the number of balls that Andy draws. only 7 of the 45 numbers are winning numbers.

probability that Andy's first number matches one of the seven is 7/45,
probability that Andy's second number matches one of the remaining 6 is 6/44,
and so on ...
Candice lim
Candice Lim
1 year ago
Ooops, I have overlooked. I actually asked a pretty silly question. Haha...I got it.

Thank you so much for taking the time to answer my question, I really appreciate your help and advice :)