Final answer:
To estimate 0.00007431 to the nearest hundred thousandths, we round it to 0.000074, which can also be represented as 7 x 10⁻⁵ when using scientific notation.
Step-by-step explanation:
To estimate the number 0.00007431 and round it to the nearest hundred thousandth, we can employ a single digit times a power of 10. Let's examine the power of 10 that is closest to our number without exceeding it. Since our number is less than 0.0001 (10⁻⁴) but greater than 0.00001 (10⁻⁵), we should use 10⁻⁵ as our power of 10. Hence, 0.00007431 is approximately 7 x 10⁻⁵ when rounded to one significant figure. When explicitly rounding to the nearest hundred thousandths, 0.00007431 becomes 0.000074.