The probability density function on the interval [a, 1] is given by 1/x2 and outside this interval the value of the function is zero. The value of a is
p.d.f. in f(x)=(1x,a≤n≤10,othewise
for p.d.f we have
∫∞−∞f(x)dx=1
⇒ ∫1af(x)dx=1
⇒ ∫1a(1x2)dx=1
⇒ [−1x]1a=1⇒a=12