Syntel
Company
Numerical Ability
Permutation and Combination
In how many ways can the digits 2,3,5,7 and 9 be placed to form a three-digit number so that the higher order digit is always greater than the lower order digits?
1: 8
2: 9
3: 10
4: 15
Read Solution (Total 10)
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- Ans : 10 ways
Given
100th digit is always greater than the 10's digit nd unit digit
so possible numbers for 100th position are 9, 7 ,5
if we select 3, d remaining 2 can occupy 2, 5 ,7, 9 which is greater than the 100th digit...
so if d 100th digit is "9" remaining 2 digits may any 2 among 4 {2 ,3 ,5 ,7} --> 4C2 = 6
so if d 100th digit is "7" remaining 2 digits may any 2 among 3 {2 ,3 ,5} --> 3C2 = 3
so if d 100th digit is "5" remaining 2 digits may any 2 among 2 {2 ,3} --> 2C2 = 2
so totally 6 + 3 + 1 = 10ways
Ans : 10 - 10 years agoHelpfull: Yes(139) No(4)
- 3)10
The 3 digit numbers are:
975 ,973,972,953,952, 932,753,752,732,532 - 10 years agoHelpfull: Yes(23) No(1)
- answer should be 10 if we take 9 in place of 100 then it will b
4c2=6
if we take 7 as 100 then it will be 3c2 ie 3
if we take 5 as 100 then it will 2c2 ie 1
so answer is 6+3+1=10 - 10 years agoHelpfull: Yes(9) No(1)
- sorry 2C2 = 1
- 10 years agoHelpfull: Yes(5) No(1)
- 9 7 (2 3 5) 3 ways
9 5 (2 3) 2 ways
7 5 (2 3) 2 ways
5 3 2 1 way
9 3 2 1 way
7 3 2 1 way 10 is answer - 10 years agoHelpfull: Yes(3) No(0)
- its solve practically;
975,973,972,953,952,932;
753,752,732;
532;
so 6+3+1=10
- 10 years agoHelpfull: Yes(1) No(0)
- 10 ways :D
- 10 years agoHelpfull: Yes(1) No(0)
- since hu>ten>unit
5*4*3/3!=10
_ _ _ - 10 years agoHelpfull: Yes(1) No(0)
- 5P3/3!=10
here 3! indicates the arranged 3 digits should be in order. - 8 years agoHelpfull: Yes(1) No(0)
- its very simple 5c3 because we are not permuting the no. . so a particular combination will have only one kind of arrangement .
- 7 years agoHelpfull: Yes(1) No(1)
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