A number is reciprocal of the other , if the arithmetic mean of the two numbers be 13/12 then the numbers are ? 

Suppose the required number a and b. Therefore according to the condition a= 1/b and a+b/2=13/12. a+b=13/6. Now a+ 1/a= 13/6. 6a²-13a+6=0. (a-3/2)(a-2/3)=0. a=3/2 and b=2/3 or a=2/3 and b=3/2.