FT dbts

From a chess board containing 54 squares of unit length each colored black and white ,rectangle of any size is chosen

Q1 If selected rectagle is square the n probablity that in selected square no. of black squares isnt equal to white squares/

Ans is given 22+42+62+82Σr2
but shouldnt it be 12+32+52+72Σr2

Q2 If selected rectangle is square the probablity that the selected square is of the size more than 2 units and less than 6 untis

ans is 42+52+62Σr2
but shouldnt it be 32+42+52Σr2

Q3 C1 is a matrix formed by replacing all the elements in matrix Cnxn with corresponding cofactors and C2 is a matrix formed by replacing all the elements in C1 with its corresponding cofactors.Similarly C3,C4,.... are formed.If l Cnl =3/2
Prove l C l=(32)1(n-1)n

**1(n-1)n is in exponent

i couldnt understand BT soln.....plz provide a better one

10 Answers

24
eureka123 ·

plzzzzzzzzzzzzz helpppppppppppppppppppppppppp

24
eureka123 ·

????????????/

106
Asish Mahapatra ·

@eure...

for first two questions,, can u explain what u think using a diag.. i still cant seem to understand the ques, properly

24
eureka123 ·

Q1
""in selected square no. of black squares isnt equal to white squares""

that means it should be and odd numbered square na
like 1x1,3x3,5x5,7x7

becoz if it is even numbered like 2x2 then no. of white=no. of black

btw did u attempt thi sques in exam or not ?

62
Lokesh Verma ·

Eureka.. for the first part, the given ansewr is correct.. because of your own logic..

The square ahs to be of size 1 or 3 or 5 or 7

so the no of squares will be 2^2 or 4^4 or 6^6 or 8^8

Thus the answer...

24
eureka123 ·

but 2^2 means 2x2 square.... ????or am i getting confused ??[2]

62
Lokesh Verma ·

no 2^2 is the number of 7x7 squares that we can form :P

24
eureka123 ·

really !!

then plz explain me everything about this chess board concpet sir..plzzzz [17]

62
Lokesh Verma ·

There is one mistake in the problem that you have given it should have 64 and not 54 squares...

Is that the reason you are not able to figure out the answer?

24
eureka123 ·

oh..thats just a typo..its 64 squares indeed

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