# If 1/a + 1/b = 1/c and ab = c, what is the average (arithmetic mean) of a and b?

(a) 0

(b) 1

(c) 1/2

(d) 2

Solution:

Given 1/a + 1/b = 1/c ..(i)

ab = c …(ii)

(i) => (b+a)/ab = 1/c

=> (a+b)/c = 1/c (since ab = c)

=> (a+b) = 1

Arithmetic mean = (a+b)/2 = 1/2

Hence option c is the answer.