Ram ans Shyam purchased two electric tea kettles A and B of same size, same thickness, and same volume of 0.4L. They studied the specification of kettles as under Kettle A: specific heat capacity = 1680 Jkg^(-1)K^(-1) Mass = 200 g Cost = Rs. 400 Kettle B: Specific heat capacity= 2450 Jkg^(-1) K^(-1) Mass = 400 g Cost = Rs. 400 When kettle A is switched on with constant potential source, the tea begins to boil in 6 min. When kettle B is switched on with the same source separately, then tea begins to boil in 8 min. The efficiengy of kettle is defined as (Energy used for liquid heating)/(Total energy supplied) They made discussion on specification and efficiency of kettles and subsequently prepared a list of questions to draw the conclusions. Some of them are as under (assume specific heat of tea liquid as 4200J kg^(-1)K^(-1) and density 1000 kgm^(-3) Efficiency of kettle A is