Logical Qn : Assume that you have 25 horses, and you want to pick the fastest 3 horses out of those 25. In each race, only 5 horses can run at the same time because there are only 5 tracks. What is the minimum number of races required to find the 3 fastest horses without using a stopwatch?

After analyzing a bit, Here are the pointers.
- We need to put all the horses into a race ( 5 at a time ) to find out the best 3 performers.
- Maximum 5 Horses in a race, so 5 times we need to conduct.
- After 5 Races, below is the table we can draw "ORDER by best performer"

Race1H1  -  Race2H6 -  Race3H11 -  Race4H16 -  Race5H21
Race1H2  -  Race2H7 -  Race3H12 -  Race4H17 -  Race5H22
Race1H3  -  Race2H8 -  Race3H13 -  Race4H18 -  Race5H23
Race1H4  -  Race2H9 -  Race3H14 -  Race4H19 -  Race5H24
Race1H5  -  Race2H10 -Race3H15 -  Race4H20 -  Race5H25

Our Aim is to find the best three performers. so, we can eliminate last two rows.
Reason: We are least bothered about 4th and 5th best in each race.
They can not be one among top three performers.

Our Target table is

Race1H1  -  Race2H6 -  Race3H11 -  Race4H16 -  Race5H21
Race1H2  -  Race2H7 -  Race3H12 -  Race4H17 -  Race5H22
Race1H3  -  Race2H8 -  Race3H13 -  Race4H18 -  Race5H23

Now Race # 6: all top players in each race:
i.e
Race1H1  -  Race2H6 -  Race3H11 -  Race4H16 -  Race5H21

Assume results are, 1st place Race1H1  ; 2nd place Race2H6 ; 3rd place Race3H11


Now Race # 7: will gives the 2nd and 3rd place horse.
i.e we need to conduct a race with below set.
                 -  Race2H6 -  Race3H11
Race1H2  -  Race2H7
Race1H3

why we eliminated other horses?

Elimination Set # 1
Race4H16 -  Race5H21
Race4H17 -  Race5H22
Race4H18 -  Race5H23

Reason: As 3rd best horse is Race3H11. so, above set is definitely is not in 1,2,3 positions.

Elimination Set # 2
Race3H12
Race3H13

Reason: same as above.

Elimination Set # 3
Race2H8

Reason: as Race1H1 is 1st , there may be chance for 2nd is Race1H2 or Race2H6
chance for 3rd is Race1H3, Race2H6, Race2H7, Race3H11
but not Race2H8

so, Answer is 7



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