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31.

From a certain population, the probability of choosing a colour blind man is 120 and that of a colour blind woman is  110 . If a randomly chosen person is found to be colour blind, then the probability that a person is a man is 


A) 29

B) 23

C) 13

D) 19



32.

 Two distributions A and B have the same mean. If their  coefficients of variation are 6 and 2 respectively  and σA,σB are their standard deviations, then


A) σA=3σB

B) 3σA=σB

C) σA=2σB

D) 2σA=σB



33.

The equation of the  plane passing through the points with position vectors A(2ˆi+6ˆj6ˆk), B(3ˆi+10ˆj9ˆk)  and C(5ˆi6ˆk)  is 


A) r.(2ˆiˆj2ˆk)=2

B) r.(ˆi2ˆjˆk)=1

C) r.(2ˆi+ˆj2ˆk)=3

D) r.(ˆi+2ˆj2ˆk)=3



34.

In a \triangle ABC, sin A and sin B satisfy   c^{2}x^{2}-c(a+b)x+ab=0 , then 


A) the triangle is acute angled

B) the triangle is obtuse angled

C) \sin C= \frac{\sqrt{3}}{2}

D) \sin A+ \cos A= \frac{a+b}{c}



35.

If \alpha  is a root of z^{2}+z+1=0  , then 

\left(\alpha^{2014}+\frac{1}{\alpha^{2014}}\right)+\left(\alpha^{2015}+\frac{1}{\alpha^{2015}}\right)^{2}

+\left(\alpha^{2016}+\frac{1}{\alpha^{2016}}\right)^{3}+\left(\alpha^{2017}+\frac{1}{\alpha^{2017}}\right)^{4}+\left(\alpha^{2018}+\frac{1}{\alpha^{2018}}\right)^{5}=


A) 8

B) 5

C) 7

D) -5



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