# In which of the following cases is the mean not typical? (statistics))

1. Oct 2, 2009

### feelgooddan

1) My wife and I are very athletic. Between us, we jog an average of 5 miles a day. My wife jogs 10.

2) In freeway driving, my car averages 32 miles per gallon.

3) Last year my car repairs averages \$48 per month.

4) The average statistician has 3.46 children.

5) The average fuse time for army's hand grenades is 4 seconds.

6) Lake Michigan is a bit deep for swimming. Its average depth is 274 feet.

2. Oct 2, 2009

### chemisttree

This is a homework question? Holy cow! Sounds like an avertisement for Wolframalpha.

3. Oct 2, 2009

### feelgooddan

It is not a homework question! Just a question from statistic book!

4. Oct 3, 2009

### CompuChip

I don't know the term "typical mean".
What does your book give as the definition?

5. Oct 4, 2009

### feelgooddan

Not typical mean is if there is a large standard deviation. In other cases it is typical.

6. Oct 4, 2009

### CompuChip

"a large" standard deviation doesn't sound very mathematical.

Anyway, how about you start by estimating the standard deviation of the cases you posted; or at least the average deviation from the mean (i.e. the order of magnitude of x - <x>).

7. Oct 4, 2009

### feelgooddan

How can I estimate the standard deviation from these data?

8. Oct 4, 2009

### CompuChip

Well, it is related to the spread of the values around the average value.
In 1) you said that your wife jogs 10 miles and you none. Do you think that the standard deviation is larger or smaller than in the case where she jogs 6 miles and you run 4?

9. Oct 4, 2009

### feelgooddan

I guess in the first case the spread is larger. So, in the second is smaller.