(a) The diameter of Earth at the equator is 7926.381 mi. Round this number to three significant figures and express it in standard exponential notation.

Key Concepts

Significant Figures

Significant figures are the digits in a number that contribute to its precision. This includes all non-zero digits, any zeros between significant digits, and trailing zeros in the decimal portion. When rounding a number, it is essential to retain the correct number of significant figures to accurately represent the precision of the measurement.

Rounding Rules

Rounding rules dictate how to adjust a number to the nearest desired place value. When rounding to three significant figures, if the digit following the last significant figure is 5 or greater, the last significant figure is increased by one. If it is less than 5, the last significant figure remains unchanged, ensuring the number is expressed accurately.

Standard Exponential Notation

Standard exponential notation expresses numbers as a product of a coefficient and a power of ten. This format is useful for simplifying large or small numbers, making them easier to read and compare. For example, the number 7926.381 can be expressed as 7.926381 x 10^3, which highlights its magnitude while maintaining precision.