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There is a 30 cm line marked at each cm and an insect is placed at eve 02 Apr 2016, 11:47
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75% (hard)

Question Stats:

59% (02:48) correct 41% (02:45) wrong based on 127 sessions

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There is a 30 cm line marked at each cm and an insect is placed at every cm. 9 frogs are trained to jump a constant distance. the first one jumps 2cm in every leap, second one jumps 3cm and so on till 9th one jumps 10cm in every leap and they eat any insect that is available at that spot. If all of them start from start line and finish the entire 30cm, how many insects were still left after the race got over.
A) 0
B) 4
C) 6
D) 7
E) 10
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D
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There is a 30 cm line marked at each cm and an insect is placed at eve 02 Apr 2016, 19:34
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chetan2u
There is a 30 cm line marked at each cm and an insect is placed at every cm. 9 frogs are trained to jump a constant distance. the first one jumps 2cm in every leap, second one jumps 3cm and so on till 9th one jumps 10cm in every leap and they eat any insect that is available at that spot. If all of them start from start line and finish the entire 30cm, how many insects were still left after the race got over.
A) 0
B) 4
C) 6
D) 9
E) 10


OA after 2 days
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Only prime numbers greater than 10 and less than 30 were let
11,13,17,19,23,29
total=6
Ans=C
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There is a 30 cm line marked at each cm and an insect is placed at eve 02 Apr 2016, 20:11
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chetan2u
There is a 30 cm line marked at each cm and an insect is placed at every cm. 9 frogs are trained to jump a constant distance. the first one jumps 2cm in every leap, second one jumps 3cm and so on till 9th one jumps 10cm in every leap and they eat any insect that is available at that spot. If all of them start from start line and finish the entire 30cm, how many insects were still left after the race got over.
A) 0
B) 4
C) 6
D) 9
E) 10

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I think the answer should be 7. Since all of them start from start line (if you see a ruler, the line starts from 0), and the minimum leap is 2 cm. So no frog jumps to 1 cm point. Answer should be 1 followed by primes greater than 10 and less than 30. i.e. 1, 11, 13, 17, 19, 23, 29.
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There is a 30 cm line marked at each cm and an insect is placed at eve Updated on: 02 Apr 2016, 20:22
Originally posted by rohit8865 on 02 Apr 2016, 20:20.
Last edited by rohit8865 on 02 Apr 2016, 20:22, edited 1 time in total.
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Vyshak
chetan2u
There is a 30 cm line marked at each cm and an insect is placed at every cm. 9 frogs are trained to jump a constant distance. the first one jumps 2cm in every leap, second one jumps 3cm and so on till 9th one jumps 10cm in every leap and they eat any insect that is available at that spot. If all of them start from start line and finish the entire 30cm, how many insects were still left after the race got over.
A) 0
B) 4
C) 6
D) 9
E) 10


I think the answer should be 7. Since all of them start from start line (if you see a ruler, the line starts from 0), and the minimum leap is 2 cm. So no frog jumps to 1 cm point. Answer should be 1 followed by primes greater than 10 and less than 30. i.e. 1, 11, 13, 17, 19, 23, 29.
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yes the same doubt is also with me but i marked C because from my view it never exceeds 7. atleast it should be 6 in any other case.
also we have to consider any insect at 0 must be eaten by any frog.
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There is a 30 cm line marked at each cm and an insect is placed at eve 02 Apr 2016, 20:22
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Vyshak
chetan2u
There is a 30 cm line marked at each cm and an insect is placed at every cm. 9 frogs are trained to jump a constant distance. the first one jumps 2cm in every leap, second one jumps 3cm and so on till 9th one jumps 10cm in every leap and they eat any insect that is available at that spot. If all of them start from start line and finish the entire 30cm, how many insects were still left after the race got over.
A) 0
B) 4
C) 6
D) 9
E) 10


I think the answer should be 7. Since all of them start from start line (if you see a ruler, the line starts from 0), and the minimum leap is 2 cm. So no frog jumps to 1 cm point. Answer should be 1 followed by primes greater than 10 and less than 30. i.e. 1, 11, 13, 17, 19, 23, 29.
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Hi,
typo error..
9 was supposed to be 7..
Edited .. Thanks
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There is a 30 cm line marked at each cm and an insect is placed at eve 02 Apr 2016, 20:27
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Vyshak
chetan2u
There is a 30 cm line marked at each cm and an insect is placed at every cm. 9 frogs are trained to jump a constant distance. the first one jumps 2cm in every leap, second one jumps 3cm and so on till 9th one jumps 10cm in every leap and they eat any insect that is available at that spot. If all of them start from start line and finish the entire 30cm, how many insects were still left after the race got over.
A) 0
B) 4
C) 6
D) 9
E) 10


I think the answer should be 7. Since all of them start from start line (if you see a ruler, the line starts from 0), and the minimum leap is 2 cm. So no frog jumps to 1 cm point. Answer should be 1 followed by primes greater than 10 and less than 30. i.e. 1, 11, 13, 17, 19, 23, 29.

Hi,
typo error..
9 was supposed to be 7..
Edited .. Thanks
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Now the OA should be D

1,11,13,17,19,23,29
Toatal=7
Ans D
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There is a 30 cm line marked at each cm and an insect is placed at eve 03 Apr 2016, 05:57
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There is a 30 cm line marked at each cm and an insect is placed at every cm. 9 frogs are trained to jump a constant distance. the first one jumps 2cm in every leap, second one jumps 3cm and so on till 9th one jumps 10cm in every leap and they eat any insect that is available at that spot. If all of them start from start line and finish the entire 30cm, how many insects were still left after the race got over.
A) 0
B) 4
C) 6
D) 7
E) 10


OA after 2 days
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Answer must be 7

Frog 1 = 2, 4 , 6 , 8 , 10 , 12 , 14 , 16 , 18 , 2 0 , 22 , 24 , 26 , 28 , 30
Frog 2 = 3 , 6 , 9 , 12 , 15 , 18 , 21 , 24 , 27 , 30
Frog 3 = 4,8,12,16,20,24,28
Frog 4 = 5, 10 , 15 , 20 , 25 , 30
Frog 5 = 6, 12 , 18 , 24 , 30
Frog 6 = 7, 14 , 21 , 28

On scrutinizing it reveals the following frogs are left - 1,11,13,17,19,23,29
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There is a 30 cm line marked at each cm and an insect is placed at eve 04 Apr 2016, 19:45
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chetan2u
There is a 30 cm line marked at each cm and an insect is placed at every cm. 9 frogs are trained to jump a constant distance. the first one jumps 2cm in every leap, second one jumps 3cm and so on till 9th one jumps 10cm in every leap and they eat any insect that is available at that spot. If all of them start from start line and finish the entire 30cm, how many insects were still left after the race got over.
A) 0
B) 4
C) 6
D) 7
E) 10


OA after 2 days
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Hi,
the Q tests our CONCEPTS on number properties...
each frog is basically jumping on multiples of 2,3,4,5,6,7,8,9 and 10..
WHAT does it mean?
It means insects on multiples of these numbers will be eaten by these insects..
That will leave us with ONLY prime numbers OR multiple of PRIME numbers above 10..

SO
1) Prime numbers till 30 = 11,13,17,19,23,29 = 6..
2) multiple of PRIME numbers above 10- lowest will be 11*11= 121
But we have only 30 cm so NIL
NOTE- Had the length been 130, 121 also would have been taken into consideration

3) ofcourse no one touches the insect on 1 cm=1
total 6+0+1=7
D
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There is a 30 cm line marked at each cm and an insect is placed at eve 10 Dec 2023, 20:43
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