Final answer:
To express 87,449 in scientific notation with four significant figures, it's written as 8.745 × 104. The number 0.000066600 in scientific notation with five significant figures is expressed as 6.6600 × 10-5.
Step-by-step explanation:
To express the number 87,449 in scientific notation with four significant figures, you need to place the decimal after the first digit and count the number of places you move it. In this case, the decimal is moved 4 places to the left: 8.7449 becomes 8.744. Now, we need just four significant figures, so it rounds to 8.745. This gives us 8.745 × 10 to the power of 4, or 8.745 × 104.
Writing the number 0.000066600 in scientific notation with five significant figures involves moving the decimal point 5 places to the right, giving us 6.6600 which rounds to 6.6600 with five significant figures. This becomes 6.6600 × 10 to the negative fifth power, or 6.6600 × 10-5.