See Boy Mow Chau's answer to Candice lim's Junior College 2 H2 Maths Singapore question

Boy Mow Chau's answer to Candice lim's Junior College 2 H2 Maths Singapore question.

2 Upvotes

0 Downvotes

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.

Date Posted: 2 years ago

Comments 4 add a comment

Candice Lim

2 years ago

Thank you so much Mr Chau!

Hope you have a great day ahead :)

Candice Lim

2 years 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

2 years 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

2 years 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 :)