Final answer:
In the given quantities, the estimated digit is the digit that has been rounded off or approximated. The significant digits are the digits that carry meaningful information in a number. Each quantity has a different estimated digit and number of significant digits.
Step-by-step explanation:
In the given quantities, the estimated digit is the digit that has been rounded off or approximated. The significant digits are the digits that carry meaningful information in a number. Let's analyze each quantity:
a) 0.00726: The estimated digit in this number is 6, as it has been rounded off. There are four significant digits in this number (0.0072).
b) 5,040: The estimated digit in this number is 0. There are three significant digits in this number (504).
c) 3.5001: The estimated digit in this number is 1, as it has been rounded off. There are five significant digits in this number.
d) 0.0009064: The estimated digit in this number is 6, as it has been rounded off. There are four significant digits in this number (0.0009).