Sec 4 probability Question

PSLE marks the graduation of Primary school students and their entry into Secondary schools as teenagers. Discuss all issues about Secondary schooling here.

Sec 4 probability Question

Postby student101 » Fri Oct 02, 2015 4:51 pm

How to solve this Sec 4 probability Question part (c) & (d). Appreciate i anybody can help
Image

student101
YellowBelt
YellowBelt
 
Posts: 25
Joined: Mon Aug 01, 2011 6:31 pm
Total Likes: 0


Re: Sec 4 probability Question

Postby Lavina » Fri Oct 02, 2015 6:33 pm

C) 3(3/5(2/5)^4 + 3/5(2/5)^5)

D) (2/5)^(n-1) x 3/5

Lavina
GreenBelt
GreenBelt
 
Posts: 110
Joined: Thu Jul 28, 2011 8:12 pm
Total Likes: 9


Re: Sec 4 probability Question

Postby student101 » Sat Oct 03, 2015 3:16 pm

Thanks Lavina. I understood the answer for d. But still confused with answer for c. Can give a hint for c?

student101
YellowBelt
YellowBelt
 
Posts: 25
Joined: Mon Aug 01, 2011 6:31 pm
Total Likes: 0


Re: Sec 4 probability Question

Postby XXXX » Sat Oct 03, 2015 4:37 pm

For each candidate, P(pass) is 21/25 and P(fail) is 4/25. P(pass) = 3/5 + 2/5 x 3/5

Then for 3 candidates taking test, there are 8 possible outcomes (in terms of pass/fail), of which 3 are 1 candidate only passing; 100, 010, 001.

The probability of this outcome can be seen simply in a probability tree and is:
3 x (21/25 x 4/25 x 4/25) = 0.064512.

We multiply because it is a contingent tree, you only follow the paths in the space that give 1 pass only.

Apologies if I am wrong, a bit HAZY today.

XXXX
BlueBelt
BlueBelt
 
Posts: 391
Joined: Wed Jul 04, 2012 1:10 pm
Total Likes: 1


Re: Sec 4 probability Question

Postby student101 » Mon Oct 05, 2015 9:28 am

Thanks xxxx for your detailed solution. I think the answer is right and is same as Lavina's answer key.
Now I got both of your concept. Thanks a lot to xxxx and Lavina

student101
YellowBelt
YellowBelt
 
Posts: 25
Joined: Mon Aug 01, 2011 6:31 pm
Total Likes: 0



Pls help with this O level matrix question

Postby student101 » Mon Oct 12, 2015 10:33 pm

I dont understand part b & c of this O level matrix Q. Pls do help me. Thanks
Image

student101
YellowBelt
YellowBelt
 
Posts: 25
Joined: Mon Aug 01, 2011 6:31 pm
Total Likes: 0



Return to Secondary Schools - Academic Support