To find out how much heavier a grain of rice is than a strand of hair, we need to subtract the mass of the strand of hair from the mass of the grain of rice.
- Mass of a strand of hair: \( 2.17 \times 10^{-5} \) ounces
- Mass of a grain of rice: \( 0.002 \) ounces, which can also be expressed in scientific notation as \( 2.0 \times 10^{-3} \) ounces.
Now we perform the subtraction:
\[ \text{Difference} = \text{Mass of grain of rice} - \text{Mass of strand of hair} \]
Converting \( 0.002 \) ounces to scientific notation:
\[ 0.002 = 2.0 \times 10^{-3} \]
Now substituting the values into the difference:
\[ \text{Difference} = (2.0 \times 10^{-3}) \text{ ounces} - (2.17 \times 10^{-5}) \text{ ounces} \]
To perform the subtraction, we convert \( 2.0 \times 10^{-3} \) into a fraction with the same exponent as \( 2.17 \times 10^{-5} \):
\[ 2.0 \times 10^{-3} = 200.0 \times 10^{-5} \]
Now subtract:
\[ \text{Difference} = (200.0 \times 10^{-5}) - (2.17 \times 10^{-5}) = (200.0 - 2.17) \times 10^{-5} \]
Calculating the subtraction:
\[ 200.0 - 2.17 = 197.83 \]
So we have:
\[ \text{Difference} = 197.83 \times 10^{-5} \]
Next, we convert this into proper scientific notation. For scientific notation, we want a coefficient between 1 and 10:
\[ 197.83 \times 10^{-5} = 1.9783 \times 10^{-3} \]
Thus, the grain of rice is:
\[ \boxed{1.9783 \times 10^{-3}} \text{ ounces heavier than the strand of hair.} \]