k is either 115 or 143, depending if its single core cable or multicore. 160 is the temp.
143 is k value for thermosetting, 115 for thermoplastic, therefore answer is 3.67
As it is computerised, you have to be spot on with the answer, an assessor may have accepted 3.6 or 3.7 but I was marked incorrect on a computerised test paper for doing just that, rounding to nearest decimal point when the answer should have been to nearest 2 decimal points.