About how many times larger is the diameter of the Milky Way Galaxy than the diameter of Saturn’s rings? (Data: Saturn’s rings are about 270,000 km in diameter; the Milky Way is 100,000 light-years in diameter.)

Josh,

This is an example of unit conversion problem, whereby you alternate the units of numerators and denominators to convert from one unit of measurement to another. This is more easily done when you convert the values into scientific notation.

The S.I. measurement for a lightyear is 9.461×10

^{15}m.Now, using the numerator-denominator method of conversion and scientific notation:

1.0x10

^{5}ly × 9.461×10^{15}m × 1km = 9.461x10^{17}km 1ly 1.0x10

^{3}mDividing:

9.461x10

^{17}km =**3.5x10**^{12}times larger2.7x10

^{5}kmNote that with scientific notation, the number of significant figures is the least amount of significant figures of all given values, with in this case, because of 2.7x10

^{5}, is 2. Thus the answer is rounded to 3.5x10^{12}.Please let me know if you need me to clarify any of these concepts further.