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
(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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14 Answers
44U're sure that we need not consider the sizes and select only based on colours??
1yup.......this answer(64) is given for different sizes (i have not asked in the question)
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.