here for every 50K change,rate constant doubles.
the overall change is 150K.so if rate constant doubles for every 50K change then according to the graph the overall change in rate constant should be 2^3 or 2×2×2 that is 8.now the initial rate constant is 0.5×10^8 and thus final rate constant will increase by 2^3 or 8 times that is 8×0.5×10^8 or 4×10^8......in ur question the rate constant doubles by 10C while here it doubles for every 50K change......the logic is same.....now compare by urself who is correct book or u......