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03 Jun 2024, 07:37
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Must: 30
Must not: 31
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
5%
(low)
Question Stats:
91% (01:31) correct
9%
(02:39)
wrong
based on 799
sessions
History
Date
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Result
Not Attempted Yet
In a variant of Hopscotch game being played by three friends, 100 small square blocks are made in a line and numbered 1 to 100 consecutively. The kids are then asked to choose a digit from 2, 3 and 5. The kid has to cross all the 100 blocks by jumping on every second, third or fifth block depending on the digit chosen.
If the probability to choose any of the 3 digit is same, select for Must the block number that would surely be stepped by all three friends and select for Must not the block number that would surely not be stepped on by all three.
If the probability to choose any of the 3 digit is same, select for Must the block number that would surely be stepped by all three friends and select for Must not the block number that would surely not be stepped on by all three.
| Must | Must not | |
| 30 | ||
| 31 | ||
| 32 | ||
| 33 | ||
| 34 | ||
| 35 |
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Official Answer
Must: 30
Must not: 31
03 Jun 2024, 08:40
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Must
All three friends will step on the blocks that are multiples of 2, 3, and 5. These are the blocks that are multiples of the least common multiple (LCM) of 2, 3, and 5.
The LCM of 2, 3, and 5 is 2*3*5 : = 30
Must not
Blocks that are not multiples of 2, 3, or 5
- 30 multiple of all 3 numbers
- 31 not a multiple of any of them but continue in order to check
- 32 multiple of 2
- 33 multiple of 3
- 34 multiple of 2
- 35 multiple of 5
So 31 should be "must not" number
All three friends will step on the blocks that are multiples of 2, 3, and 5. These are the blocks that are multiples of the least common multiple (LCM) of 2, 3, and 5.
The LCM of 2, 3, and 5 is 2*3*5 : = 30
Must not
Blocks that are not multiples of 2, 3, or 5
- 30 multiple of all 3 numbers
- 31 not a multiple of any of them but continue in order to check
- 32 multiple of 2
- 33 multiple of 3
- 34 multiple of 2
- 35 multiple of 5
So 31 should be "must not" number
17 Jun 2024, 13:29
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In a variant of Hopscotch game being played by three friends, 100 small square blocks are made in a line and numbered 1 to 100 consecutively. The kids are then asked to choose a digit from 2, 3 and 5. The kid has to cross all the 100 blocks by jumping on every second, third or fifth block depending on the digit chosen.
If the probability to choose any of the 3 digit is same, select for Must the block number that would surely be stepped by all three friends and select for Must not the block number that would surely not be stepped on by all three.
> To step on the same block, this question is essentially asking for the LCM. So the LCM(2,3,5) is 30. Everyone will hit Block #30 at some point.
> Find a number that is NOT divisible by 2,3,5. Only '31' applies here.
If the probability to choose any of the 3 digit is same, select for Must the block number that would surely be stepped by all three friends and select for Must not the block number that would surely not be stepped on by all three.
> To step on the same block, this question is essentially asking for the LCM. So the LCM(2,3,5) is 30. Everyone will hit Block #30 at some point.
> Find a number that is NOT divisible by 2,3,5. Only '31' applies here.
