07 mc ce maths Q.27.Q53,Q54

27. sum of exterior angles of any polygon is degree 360.
180x(n-2)=4x360
n=10
53. there are 13 balls.
P(both black balls)+P(both white balls)
(8/13)x(7/12)+(5/13)x(4/12)
=19/39
54.P(different letters)
=1-P(same letters)
=1-[(1/4)x(1/4)+(1/4)x(1/4)]
=7/8

That mean 07 maths Question number 27, 53&54.