Latest self Aptitude Question SOLUTION: the number of straight lines that can be dranw out of 10 points of which 7 are collinear? pls explain the answers for all these questions..

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(#M40013129) SELF question permutation and combination Keep an EYE

the number of straight lines that can be dranw out of 10 points of which 7 are collinear?

pls explain the answers for all these questions..

manisha (11 years ago)

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chakravarthi  (11 years ago)

10C2-7C2+1(7 COLLINEAR SINGLE STRAIGHTLINE)=24

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Smita  (11 years ago)

10C2-7C2+1 = 45 -21+1= 25

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Piyush Jain  (11 years ago)

answer: 45

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manisha  (11 years ago)

the options available are
24 , 23 , 25 , 21

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srikhakollu bharghav  (11 years ago)

i think answer is 25...
7c1 x 3c1 = 21...and the 7 collinear points forms 1 straight line...so 21+1=22 and we have 3 points which are not collinear.. so 3c2 = 3...so answer is
22+3=25....

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masood ahmad  (11 years ago)

10 lines can be drawn, as the points are 10
coz every line has a single point.

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Jaikrishna Kumar  (11 years ago)

straight line can be formed by joining 2 points

so number of ways in which we can select 2 points from 10 points is = 10C2

but it also include that in which 4 points are in straight line . from those 4 points only one line can be formed .

so we have to subtract 4C2 -1 from above result

so total lines are = 10C2 - 4C2 + 1

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