# Lesson 4 Wow, That’s Weird! Practice Understanding

## Learning Focus

Compare normal distributions.

What methods can we find for using mean and standard deviation to compare normal distributions?

How can we decide if an event that seems weird is actually unusual or fairly likely?

## Open Up the Math: Launch, Explore, Discuss

Each of the scenarios below is based upon normal distributions. Rank these scenarios from most unusual to most average. (

### 1.

#### a.

The number of red loops in a box of Tutti-NoFrutti-Os is normally distributed with mean of

Rank:

Explanation:

#### b.

The weight of house cats is normally distributed with a mean of

Rank:

Explanation:

#### c.

The lifetime of a battery is normally distributed with a mean life of

Rank:

Explanation:

#### d.

The amount that a human fingernail grows in a year is normally distributed with a mean length of

Rank:

Explanation:

#### e.

My little brother was digging in the garden and found a giant earthworm that was

Rank:

Explanation:

#### f.

The mean length of a human pregnancy is

Rank:

Explanation:

#### g.

IQ scores for young adults on a famous IQ test are distributed normally with a mean of

Rank:

Explanation:

#### h.

The army measured head sizes among male soldiers and found that the distribution is pretty close to normal with a mean of

Rank:

Explanation:

## Ready for More?

Write your own weird situation like the ones given in the task with:

#### a.

A

#### b.

A z-score between

#### c.

A

## Takeaways

Strategies for comparing events on normal distributions:

## Lesson Summary

In this lesson, we used features of a normal distribution—including the symmetry, the mean, and the standard deviation—to determine how unusual a given event may be.

### 1.

Before teaching a lesson about boarding cats and dogs, Mrs. Jones decided to survey each of her classes to find out about her students’ animal preferences. Here is her data:

1st hour | 2nd hour | 3rd hour |
---|---|---|

C C C C C C C C C C C C C C C C C C C C C C C D D D D D D D D N N | C C C C C C C C C C C C D D D D D D D D D D D D D D D D D D D D N N N | C C C C D D D D D D D D D D D D D D D D D D D D D D D D D N N N N N |

1st | 2nd | 3rd | total | |
---|---|---|---|---|

prefer cats | ||||

prefer dogs | ||||

no pets - no preference | ||||

total |

### 2.

Solve for