Question

In a colony of 100 blocks of flats numbering 1 to 100, a school van stops at every sixth block while a school bus stops at every tenth block. On which stops will both of them stop if they start from the entrance of the colony?

Answer 1

Hi ,

Number blocks in a colony is 100 and numbering 1 to 100.

If a school van stops at every sixth block

while

a school bus stops at every tenth block then

Flat numbers they stopped are

Flat numbers van stops

= { 6 , 12 ,18 , 24 , 30 , 36 , 42 , 48 , 54 , 60 , 66 ,

72 , 78 , 84 , 90 , 96 }

Flat numbers bus stops

= { 10 , 20 ,30 , 40 , 50 ,60 ,70 , 80 ,90 , 100 }

Common flat numbers = { 30 , 60 , 90 }

Therefore ,

30 , 60 and 90 flat numbers are common bus stops


of Van and Bus .

Or

You can find LCM of 6 and 10 we get 30

Then find multiples of 30 less than 100 are

required flat numbers .

Multiples of 30 less tha 100 = { 30 , 60, 90 }

I hope this helps you.

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Answer 2

First find LCM of 6 and 10.

2-6,10

3-3,5

5-1,5

1,1.

LCM=2×3×5=30

find multiples of30 less than 100(30,60,90)

multiples less tan 100 are the answers

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