Elitmus
Exam
Numerical Ability
Permutation and Combination
serlok homes and watson have to travel from rajiv chowk to airport by metro.they have enough amount of 1,5,25 paise coin. homes agrees to pay for watson only if he tells the possible combination of coin used to pay for the ticket.
1. how many combinations are possible if the fair is 50 paise??
2. how many combinations are possible if the get discount of 10%. i.e the fare is 45 paise??
Read Solution (Total 5)
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- Let us assume that there are x,y and z number of coins of 1 paisa, 5 paisa and 25 paisa. then according to question we can write x+5y+25z=50.
so possible value for z will be 0,1and2. when z=o i.e x+5y=50 hence possible pair for x and y will be (0,10),(5,9),(10,8)........(50,0) total is 11.
when z=1 i.e x+5y=25 hence possible pair for x and y will be (0,5),(5,4),(10,3)........(25,0) total is 6.
when z=2 i.e x+5y=0 hence possible pair for x and y will be only (0,0)total number is 1.
1)hence total possible combination will be 11+6+1=18.
and for 2)....according to question we can write x+5y+25z=45.
so possible value for z will be 0 and1.
when z=o i.e x+5y=45 hence possible pair for x and y will be 10
and when z=1 i.e x+5y=20 hence possible pair for x and y will be 5.
2)hence total possible combination will be 10+5=15.
- 10 years agoHelpfull: Yes(17) No(0)
- lets first consider the cases of 1,5 and 10. We do not consider the cases of 25, as of now
If 10 coins = 5, 5 and 1 coins = 0, 1 possibility
If 10 coins = 4, 5 coins = 0,1,2 3 possibilities
If 10 coins = 3, 5 coins = 0,1,2,3,4 5 possibilities
If 10 coins = 2, 5 coins = 0,1,2,3,4,5,6 7 possibilities
If 10 coins = 1, 5 coins = 0 to 8 9 possibilities
If 10 coins = 0, 5 coins = 0 to 10 11 possibilities
36 possibilities
Now the case 25 paise coins
25 coins = 2 1 possibility
25 coins = 1 now we consider the sub-possibilitites of this case
10 coins = 2, 5 coins= 0,1 2 possibilities
10 coins =1, 5 coins = 0,1,2,3 4 possibilities
10 coins = 0, 5 coins = 0,1,2,3,4,5 6 possibilities
Total 13 possibilities from this case
Total possibilities = 36 +13 = 49 possibilities - 11 years agoHelpfull: Yes(8) No(3)
- Now the case of fare of 45 paise
lets first consider the cases of 1,5 and 10. We do not consider the cases of 25, as of now
If 10 coins = 4, 5 coins = 0,1 2 possibility
If 10 coins = 3, 5 coins = 0,1,2,3 4 possibilities
If 10 coins = 2, 5 coins = 0,1,2,3,4,5 6 possibilities
If 10 coins = 1, 5 coins = 0,1,2,3,4,5,6,7 8 possibilities
If 10 coins = 0, 5 coins = 0 to 9 10 possibilities
30 possibilities
Now the case 25 paise coins
25 coins = 1 now we consider the sub-possibilitites of this case
10 coins = 2, 5 coins= 0 1 possibilities
10 coins =1, 5 coins = 0,1,2 3 possibilities
10 coins = 0, 5 coins = 0,1,2,3,4 5 possibilities
Total 9 possibilities from this case
Total possibilities = 30 +9 = 39 possibilities - 11 years agoHelpfull: Yes(2) No(4)
- sorry they have enough coins of 1,5,10&25 paise
- 11 years agoHelpfull: Yes(1) No(2)
- (15)
x+5y+25z=50
at z=0, x+5y=50 then y can have 10 possible values.
at z=1 x+5y=25 then y can have 5 possible values.
at z=2 x+5y=0 then y can have 0 possible values.
so total combinations will be 15. - 10 years agoHelpfull: Yes(1) No(0)
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