• We need YOUR help for the next generation of students! Upload your notes and exams on our Notes & Resources page!
  • You must be a registered member to download resources

General Maths 2015 HSC error? (1 Viewer)

sourmilk

Active Member
Joined
Apr 14, 2015
Messages
189
Gender
Female
HSC
2016
http://www.boardofstudies.nsw.edu.au/hsc_exams/2015/exams/2015-hsc-maths-general-2.pdf

For question 18 it asks:

A Student Representative Council (SRC) consists of five members. Three of the members
are being selected to attend a conference.
In how many ways can the three members be selected?
(A) 10
(B) 20
(C) 30
(D) 60

Isn't the answer D? Apparently in the answers the answer is A. Both me and my friend got D and we don't know how it's A, and I literally wrote all the possible combinations and it's definitely more than 10.
 

davidgoes4wce

Well-Known Member
Joined
Jun 29, 2014
Messages
1,884
Location
Sydney, New South Wales
Gender
Male
HSC
N/A
I went through that question today , and I thought the answer was A.



It doesn't matter about the 'order' of the selections. (*Unordered selection)
 

sourmilk

Active Member
Joined
Apr 14, 2015
Messages
189
Gender
Female
HSC
2016
I went through that question today , and I thought the answer was A.



It doesn't matter about the 'order' of the selections. (*Unordered selection)
OoooooooooOOh thank you so much! my friend told me to dismiss that it was wrong ahahahaha
 

Mongoose528

Member
Joined
Jun 30, 2016
Messages
72
Location
WA
Gender
Male
HSC
2019
For combinations without repetition, the formula is n!/r!(n-r)!

Where n is the number of things to choose from and r is the amount of things we chose

So in this question, there are 5 people to choose from and we have to choose 3 of them

So the amount of ways is 5!/(3!(5-3)!) = 5!/(3!2!) = 120/(6*2) = 120/12 = 10
 
Last edited:

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top