Question

there are about 31,500,000 seconds in a year. what is the best approximation of the number of seconds in a year? a 3 x 10^6 seconds b 3 x 10^7 seconds c 3 x 10^5 seconds d 3 x 10^8 seconds

Explanation:

Step1: Write 31,500,000 in scientific - notation

The number 31,500,000 can be written as $3.15\times10^{7}$ since moving the decimal point 7 places to the left gives us a number between 1 and 10.

Step2: Approximate the number

Since 3.15 is close to 3, an approximation of $3.15\times10^{7}$ is $3\times10^{7}$.

Answer:

B. $3\times 10^{7}$ seconds