There may be cases where an extensometer is used in the metal tensile test and cases where it is not. At this time, explain the part where the most difference appears in analyzing the results of the two experiments.

At operating stress of 420MPa, the number of cycles to fail a specimen is 65 cycles. At operating stress of 360MPa, the number of cycles to fail the specimen is 390 cycles, and at operating stress of 130MPa, the number of cycles to fail the specimen is 11,900 cycles. A test sequence as follows is designed: first, operating stress of 420MPa for 7 cycles, second, operating stress of 360MPa for 65 cycles, and third, operating stress of 130MPa for 325 cycles. Determine at what number of cycle and which operating stress level the specimen would be expected to fail if the above sequence is repeated.