Find the z-score corresponding to a raw score of 132 from a normal distribution with mean 100 and standard deviation 15.

Solution

We compute

132 - 100
z = = 2.133
15

Example

A z-score of 1.7 was found from an observation coming from a normal distribution with mean 14 and standard deviation 3. Find the raw score.

Solution

We have

x - 14
1.7 =
3

To solve this we just multiply both sides by the denominator 3,

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5.1 = x - 14

Loop mash up pro 1 0 48. x = 19.1

The z-score and Area

Often we want to find the probability that a z-score will be less than a given value, greater than a given value, or in between two values. To accomplish this, we use the table from the textbook and a few properties about the normal distribution.

Example

Find

P(z < 2.37)

Solution

We use the table. Notice the picture on the table has shaded region corresponding to the area to the left (below) a z-score. This is exactly what we want. Below are a few lines of the table.

z.00.01.02.03.04.05.06.07.08.09
2.2.9861.9864.9868.9871.9875.9878.9881.9884.9887.9890
2.3.9893.9896.9898.9901.9904.9906.9909.9911.9913.9916
2.4.9918.9920.9922.9925.9927.9929.9931.9932.9934.9936

The columns corresponds to the ones and tenths digits of the z-score and the rows correspond to the hundredths digits. For our problem we want the row 2.3 (from 2.37) and the row .07 (from 2.37). The number in the table that matches this is.9911.

Hence

P(z < 2.37) = .9911

Example

Historyhound 2 1 15 Kjv

Find

Historyhound 2 1 15

P(z > 1.82)

Solution

In this case, we want the area to the right of 1.82. This is not what is given in the table. We can use the identity

P(z > 1.82) = 1 - P(z < 1.82)

reading the table gives

P(z < 1.82) = .9656

Our answer is

P(z > 1.82) = 1 - .9656 = .0344

Example

Find

P(-1.18 < z < 2.1)

Solution

Once again, the table does not exactly handle this type of area. However, the area between -1.18 and 2.1 is equal to the area to the left of 2.1 minus the area to the left of -1.18. That is

P(-1.18 < z < 2.1) = P(z < 2.1) - P(z < -1.18)

To find P(z < 2.1) we rewrite it as P(z < 2.10) and use the table to get

P(z < 2.10) = .9821.

The table also tells us that

P(z < -1.18) = .1190

Now subtract to get

P(-1.18 < z < 2.1) = .9821 - .1190 = .8631

e-mail Questions and Suggestions

HistoryHound 2.2 is now available, giving you the option to add its icon to your menu bar so you can search your browsing history even faster.
HistoryHound still finds text in all the pages you’ve visited in any of the major Mac web browsers, but now handles Chrome and Firefox power users better. If you use multiple user profiles or run both Firefox and Firefox Developer Edition, HistoryHound will now track and search your history more efficiently and accurately.
This release also eliminates delays that could occur when you have HistoryHound set to “search as you type,” and adds a contextual menu to its error window so you can quickly add filters to keep certain pages from being added to your search index.
Release notes and download links are on the HistoryHound Release page.