# Homework Help: Simple average question using sig figs within ± 0.0 of uncertainty?

1. Jan 20, 2012

### bobi

Simple average question using sig figs within ± 0.0 ?

1. The problem statement, all variables and given/known data

Consider the following measurements of mileages:
23.8 mph, 20.1 mph, 26.5 mph, 20.7 mph, 21.7 mph, 27.6 mph,
30 mph, 28 mph, 27.4 mph, 34.3 mph, 26.5 mph, 32.7 mph.
What is the average mileage (using sig figs)?

2. Relevant equations

Avg=Total Sum/number of variables

3. The attempt at a solution

The average calculated was 26.60833333. And Since two variables have only two sig figs, I thought the answer should be 27. But it was a wrong answer.
But the last part of question asked the answer to be within ± 0.0 mph.

What does 'within ± 0.0 mph' means? No uncertainty? Or typo of 0.1 or 0.01?
What should be the correct answer?

Last edited: Jan 20, 2012
2. Jan 20, 2012

### I like Serena

Welcome to PF, bobi!

'within ± 0.0 mph' means within ± 0.05 mph.
That is, with 1 digit after the decimal point.
So your average would be 26.6 ± 0.0 mph

3. Jan 20, 2012

### bobi

Thanks a lot!!