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ahh okay i understand Q3 and 28, but i still dont' know how to do question 22. Also does anyone know how to do Q27c)?

3.a) An urn contains 3 white balls, 4 red balls and 5 black balls. Three balls are drawn at random. What is the probability that they are different colours? (answer = 3/11) 22. Urn A contains 6 white and 4 black balls. Urn B contains 2 white and 2 black balls. From urn A two balls are...

haha thats reassuring i guess. I hate perms and combs. It gives me a headache :cry:

oooh. so out of the 11 chosen, only a maximum 5 can be bowlers and a maximum 2 be wicketkeepers?

Ohhhhhh.... But in the question there's no restriction for the number of batsman that the team can have. So couldn't we continue and do combinations like: 6 bowl, 2 wick, 3 bat 7 bowl, 2 wick, 2 bat or.... 5 bowl, 3 wick, 3 bat.. etc

bump. Q11 anyone?

In how many ways can 8 girls be divided into 4 sets of 2? (answer = 105)

alright. Thank you very much.

11. An eleven is to be chosen from 15 cricketers of whom 5 are bowlers only, 2 others are wicketkeepers only and the rest are batsman only. How many possible elevens can be chosen which contain at least 4 bowlers and at least 1 wicketkeeper? (answer = 742 18. In how many ways can n things be...

for question 7... when i did it i only considered the number of possible commitees when B is included meaning A isn't. ie. 8C5 = 56. How come i also have to consider when A is included and B isn't, and when neither A or B is included? Oh wait nevermind what i just said i get it now. The...

Hey guys... again.... I finished the permutations exercise thanks to all the help you guys provided. But now i'm doing combinations and i'm bad at this too. Anyway these are the questions i couldn't get correct so far.... :( 7. A committee of 6 is to be selected from 10 people of whom A and B...

nevermind. lychnobity clarified it.

This question seems a bit ambiguous. Did it mean that there has to be exactly 3 letters between e and i? Or did it mean a minimum of 3 letters between e and i? You're solution assumes 3 or more letters apart right? :S

Ahh okay. So in this question do we just disregard the driver since they are confined to one position?

Hey guys i fail at this topic. Need some help in figuring out how these questions are done. Much appreciated :cry: 23. Find the number of arrangements of the letters in the word pencils if: i) e precedes i (answer = 2520) ii) there are 3 letters between e and i (answer = 720) 28. A car can...

thanks!:D

Hey guys i can't do these permutation questions :S Could someone please show me how they are solved. These questions are all from fitzpatrick 3unit text book exercise 28a) 4. How many five digit numbers can be formed from the digits 2,3,5,6,8,9 if no digit can be used more than once in a...

why do you worry so much about this stuff Zazzy?! Just go study you silly person :vcross:

coool thanks guys.. I was just a bit confused because in this question i didn't know what the centre of motion was so i didn't know if i should use either: i) v^2 = n^2(a^2 - x^2) or ii) v^2 = n^2(a^2 - (x-b)^2) And also i'm confused too about when i'm meant to choose between a positive...

The period of a particle moving in SHM is 6 s and its amplitude is 8cm. Calculate its velocity and acceleration (correct to 1 decimal place) when the displacement is 5cm from the centre of motion. :) answer: v = -6.5cm/s a = -5.5cm/s/s