Final answer:
The numbers written in standard form are 4.02 x 10², 5.3121 x 10³, 9.354 x 10⁶, and 9.307 x 10¹².
Step-by-step explanation:
The numbers written in standard form among the given options are:
- 4.02 x 10²
- 5.3121 x 10³
- 9.354 x 10⁶
- 9.307 x 10¹²
Standard form, also known as scientific notation, is a way to represent very large or very small numbers in a concise format. In standard form, a number is written as a product of a digit greater than or equal to 1 and less than 10, multiplied by a power of 10.