Question

The airline industry wants to better accommodate passengers whose flights are delayed by providing more amenities. Which measure provides the best information to the airline industry?

Answer 1

A few rules you need to know:
\[\begin{align*}
(1)~~&\text{numerals }1-9\text{ are significant}\\
(2)~~&\text{0s surrounded by numbers from (1) are significant}\\
(3)~~&\text{if you have a decimal point, all numbers (both zero and non-zero)}\\
&\text{are significant}\\
(4)~~&\text{0s that trail after after other numbers are NOT significant}\\
&\text{(unless there's a decimal point, as in (3))}
\end{align*}\]

Answer 2

With that in mind, consider a few examples.

100
has one significant digit (the 1). The two zeroes are trailing after a sig fig, and so are insignificant.

101
has three sig figs. The zero is wrapped by two sig figs, and so is also significant.

100.0
has four sig figs (due to the decimal point).

100.
has three (also due to the decimal point).

0.00001
actually has one. I forgot to add a rule, or rather an exception to a rule:
\[\color{red}{(3)~~\text{if a decimal is present, all numbers except left-trailing zeroes are significant}}\]
So as an example to distinguish this CORRECT rule from what I previously wrote:

0.01
has one sig fig, whereas

1.01
has three sig figs.

Answer 3

Do you need help with operating on numbers with these rules?

Answer 4

kind of