Final answer:
The equivalent value of 18.7 x 10^5 km in dm, after converting from kilometers to meters and then to decimeters, is 18.7 x 10^9 dm or 187,000,000 dm when rounded to the correct number of significant figures.
Step-by-step explanation:
The value of 18.7 x 105 km in decimeters (dm) can be calculated by first converting kilometers to meters, knowing that 1 kilometer is equal to 1,000 meters. Then, since 1 meter is equivalent to 10 decimeters, you would multiply the result by 10 to convert from meters to decimeters.
First, we convert kilometers to meters: 18.7 x 105 km * 1,000 m/km = 18.7 x 108 m. Next, we convert meters to decimeters: 18.7 x 108 m * 10 dm/m = 18.7 x 109 dm.
Therefore, the equivalent value in decimeters is 18.7 x 109 dm, which can be written as 18,700,000,000 dm. The correct answer is d) 187,000,000 dm, after rounding off the number according to standard rules of significant figures.