1yup.......this answer(64) is given for different sizes (i have not asked in the question)
(1)there are 24 balls of 6 different sizes in a bag, there being 4 balls of each size in four different colours .in how many ways 4 balls can be selected so that they are of differnt colours??????
(2) how many 5 digit nos. of different digits can be made in which the digits are in
(i) ascending order
(ii)descending order
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UP 0 DOWN 0 3 14
14 Answers
41) Accord to qs the size doesn't matter na
So v divide them into 4 diff groups of 4 colours each grp containing 6 balls of diif sizes
Then v need to select 1 from each group of 6
Ans : 6 4
4U're sure that we need not consider the sizes and select only based on colours??
1
1sinchan can u plz tell ur method.mine is ffrom brute force.........hope urs is more basic
1yes of course xyz
in the part (ii)
there are 5 places and nos 0,1,2,3,4,5,6,7,8,9 total 10 nos
if 0 is not present then the remaining 9 nos can arrange in ascending order in 9c5 ways i.e 9c5 selections and arrangement in only one way.
if again 0 is present it is the smallest no hence occupies only the last place .
hence the remaining 9 nos arranges in ascending order in the first 4 places in 9c4 ways.
thus total no of ways is 9c5+9c4.
in part (i) the total no of arrangement in descending order is 10c5 ways.this includes the cases where 0 occupies the first place in1*9c4 ways.
thus ans is 10c5-9c4 ways
1the answer of the ist question is 64.u r right uttara hopefully.i dont know about the given ans but it comes out to be 64.
thanks xyz for ur method.
62Q 2 ) i
there is a slightly simpler logic...
if you chose any one 5 digits from 1, 2, ... 9 you get one such number (you cannot chose zero at all!)
hence the answer is 9C5
for the 2nd part, chose any 5 of 0, 1, 2, 3... 9
10C5
1yes sir thats much simpler.
coincidentally my ans 10c5-9c4 comes out to be=9c5
62i think sinchan is correct.. the answer given seems to be wrong.
unless the question setter has something else in mind.