To find the approximate difference in mass between the blue whale and the dinosaur, we can subtract the mass of the dinosaur from the mass of the blue whale.
The mass of the blue whale is approximately \( 1.7 \times 10^5 \) kg, and the mass of the dinosaur is approximately \( 8 \times 10^4 \) kg.
We can express both masses in the same power of ten to make the subtraction easier:
\[ 1.7 \times 10^5 \text{ kg} = 1.7 \times 10^5 \text{ kg} \] \[ 8 \times 10^4 \text{ kg} = 0.8 \times 10^5 \text{ kg} \]
Now, we can subtract:
\[ \text{Difference} = 1.7 \times 10^5 \text{ kg} - 0.8 \times 10^5 \text{ kg} \] \[ \text{Difference} = (1.7 - 0.8) \times 10^5 \text{ kg} \] \[ \text{Difference} = 0.9 \times 10^5 \text{ kg} \]
Thus, the approximate difference in mass between the blue whale and the dinosaur is:
\[ 0.9 \times 10^5 \text{ kg} = 9 \times 10^4 \text{ kg} \]
Hence, the approximate difference in mass is \( 9 \times 10^4 \) kg.