Question 472794: An examination paper contains 12 different questions of which 3 are on trigonometry, 4 are on algebra and 5 on calculus. Girls are asked to answer 8 questions. Calculate:
i) the number of different ways in which a girl can select 8 questions if there is no restriction,
ii) the number of these selections which contain questions on only 2 of the 3 topics,trigonometry, algebra and calculus.
*Please answer as soon as possible bro :)
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! An examination paper contains 12 different questions of which
3 are on trigonometry,
4 are on algebra and
5 on calculus.
--------------------
Girls are asked to answer 8 questions. Calculate:
i) the number of different ways in which a girl can select 8 questions if there is no restriction,
Ans: 12C8 = 12C4 = (12*11*10*9)/(1*2*3*4) = 495
---------------------
ii) the number of these selections which contain questions on only 2 of the 3 topics,trigonometry, algebra and calculus.
Ans:
alg and trig: there are not 8 questions in the combined categories
---
alg and calc: 9C8 = 9C1 = 9 selections
---
trig and calc: 8C8 = 1 selection
====================================
Cheers,
Stan H.
|
|
|
