Q. There are 25 horses. maximum 5 horses can run a race at a time. Then what is the minimum number of race required to find top 5 horse among 25? If you don't have any timer you can rate horses only by there rank in individual race.

• we need to make 10 races.
  first, group those 25 into group of 5s and race each group. That would be 5 races. Now,we'll have ranks of each of the five groups individually.
  Let's say:
  a: 5 4 3 2 1
  b: 5 4 3 2 1
  c: 5 4 3 2 1
  d: 5 4 3 2 1
  e: 5 4 3 2 1
  now, group the top scorers from each group and make a race. You'll find the global first rank holder.
  Next, remove that horse from race and take the next one from its group. Rest of the horses will remain unaltered. Race again. You'll find the second rank holder.
  Repeat the step until you get 5 global rank holders, i.e. you'll need 5 more races.
  So, total is: 5+5=10
• 11 years agoHelpfull: Yes(25) No(6)
• we can do it only in five time .in each race we have to select one .after five race there are only five horse . now in the sixth race you can select the you have the top 1 horse
• 11 years agoHelpfull: Yes(2) No(2)
• we need to make 6 races
  Let's say:
  a: 5 4 3 2 1
  b: 5 4 3 2 1
  c: 5 4 3 2 1
  d: 5 4 3 2 1
  e: 5 4 321
• 10 years agoHelpfull: Yes(2) No(4)
• First make them 5 groups and make them race and rank them like:
  a b c d e
  f:5 4 3 2 1
  g:5 4 3 2 1
  h:5 4 3 2 1
  i:5 4 3 2 1
  j:5 4 3 2 1
  
  Now race them column wise.
  First take (e) column and make them race(1st final race) and select 1st one and that will be the top 1st among 25 horses.
  
  Second time take (d) column and make them race and select 1st one but this will not be 2nd among 25, now the 1st one from (d) column take with left 4 horses from column (e) and make them race (2nd final race) and select 1st ,and that will be 2nd among 25 horses.
  
  Now take (c) column and make them race and select 1st, and take it with 4 f
  horses left from (d) and select 1st and take it with the 4 horses left from the 2nd final race and make them race (3rd final race) and select 1st, that will be the 3rd among 25 horses.
  
  Now this process continue for column (b) & (a), and we will get 4th & 5th top horse among 25 horses.
  
  So, the minimum no of races required=5+1+(1+1)+(1+1+1)+(1+1+1+1)+(1+1+1+1+1)=20
  Ans: 20 races.
• 10 years agoHelpfull: Yes(2) No(3)
• we need to make 6 races...
  a:54321
  b:54321
  c:54321
  d:54321
  e:54321
  nd last one b the race of winners of all d above five races...
  
• 10 years agoHelpfull: Yes(2) No(1)
• Answer is 10
  firstly divide 5 groups of 5 horses and run them so, total 5 race
  then next run topper horses of all 5 groups and it will be 6th race and it will give the 1st topper
  then next run will be between 2nd topper of 6th race and other group's 2nd topper except the group from which the 2nd topper of of 6th race belongs. and it will give us our 2nd topper horse of 25 horses and it will be our 7th race.
  Similarly, in 8th run, the 3rd topper of 6th race, 2nd topper of 7th race and 3rd topper of all other groups, except group of these 2 will perform and it will give us our 3rd topper of 25 horses.
  similarly in 9th race, we will get our 4th topper horse and in 10th race the 5th topper horse we will get.
• 8 years agoHelpfull: Yes(1) No(1)
• make 5*5 group find 5 top and then make a race in these 5 u will find top
  
• 11 years agoHelpfull: Yes(0) No(8)
• 5 races. divide 25 horses into 5 batches then conduct race for 5 batches at the same time and find out which 5 are
• 11 years agoHelpfull: Yes(0) No(3)
• we need to make 6 races
  Let's say:
  a: 5 4 3 2 1
  b: 5 4 3 2 1
  c: 5 4 3 2 1
  d: 5 4 3 2 1
  e: 5 4 321
• 10 years agoHelpfull: Yes(0) No(1)
• First we take 5 horses and make them race and select first 1.
  Second other (5-1)=4 horses + 1 horse take from other 20 horse, and make them race and select first 1.
  This process repeated 21 times and select 21 horses out of 25 horses.
  
  Now again this process repeated 17 times and select 17 horses out of 21 horses.
  
  Again repeat this process 13 times and select 13 horses out of 17 horses.
  Again repeat this process 9 times and select 9 horses out of 13 horses.
  Again repeat this process 5 times and select top 5 horses out of top 9 horses.
  
  So, total races required=(21+17+13+9+5)=65.
  Ans: 65 races.
• 10 years agoHelpfull: Yes(0) No(2)
• 6races
  In first 5races 5horses are selected and in the 6th race their ranking is decided
• 10 years agoHelpfull: Yes(0) No(2)
• there is no timer
  so we observe all horses performance individually
  so
  first race 1 2 3 4 5
  second race 6 7 8 9 10
  third 11 12 13 14 15
  fourth 16 17 18 19 20
  fifth 21 22 23 24 25
  we found in each race there is one horse first
  but there is a chance the second horse in third group is faster than first horse in second group etc.,
  for this reason we shall conduct 25 races
  to selet the top five horses
  
  
• 10 years agoHelpfull: Yes(0) No(2)
• we have 25 h and 5 will run at a time.
  so we can have 5 races consisting of 5 horses in each race
  Then out of each race one leading h will b selected
  and then in 6th race we can have the best h
  
  6
• 9 years agoHelpfull: Yes(0) No(1)
• There are 25 horses in that they can run a race at a time 5 only so totally 5races (5)+ we put races for that 5 horses(1) so there are 6 race required.
• 8 years agoHelpfull: Yes(0) No(1)
• minimum one race is enough...
• 8 years agoHelpfull: Yes(0) No(2)
• the ans is 5 because they are 25 horses 5 horse can run at a time so 5*5=25 then in five race we select one horse means it become 5
• 6 years agoHelpfull: Yes(0) No(0)
• we need to make 10 races.
  first, group those 25 into group of 5s and race each group. That would be 5 races. Now,we'll have ranks of each of the five groups individually.
  Let's say:
  a: 5 4 3 2 1
  b: 5 4 3 2 1
  c: 5 4 3 2 1
  d: 5 4 3 2 1
  e: 5 4 3 2 1
  now, group the top scorers from each group and make a race. You'll find the global first rank holder.
  Next, remove that horse from race and take the next one from its group. Rest of the horses will remain unaltered. Race again. You'll find the second rank holder.
  Repeat the step until you get 5 global rank holders, i.e. you'll need 5 more races.
  So, total is: 5+5=10
• 5 years agoHelpfull: Yes(0) No(0)