Question

the length of a micrometer is approximately 0.00003937 inch. how is this number written in scientific notation?
a $0.3937 \times 10^{-4}$
b $3.937 \times 10^{-5}$
c $39.37 \times 10^{-6}$
d $3937 \times 10^{-8}$

Explanation:

Step1: Define scientific notation rule

Scientific notation is $a \times 10^n$, where $1 \leq a < 10$, $n$ is integer.

Step2: Adjust given number to fit rule

Take $0.00003937$, move decimal 5 places right: $a=3.937$, $n=-5$.
Result: $3.937 \times 10^{-5}$

Step3: Match with options

Compare to given choices, matches option B.

Answer:

B. $3.937 \times 10^{-5}$