 The data in Table 3 are the recorded birth weights of 50 infants who displayed severe idiopathic respiratory distress syndrome (SIRDS). This is a serious condition which can result in death.

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The data set in Table 2 comprises the figures published by the US Labor Department for the composition of its workforce in 1986. It shows the average numbers over the year of male and female workers in the various different employment categories and is typical of the kind of data pub
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The first data set is a very simple one. Table 1 shows the number of nuclear power stations in various countries throughout the world before the end of the cold war (that is, prior to 1989). The names of the countries listed are those that pertained at the time the data were collecte
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The data sets you will meet in this section are very different from each other, both in structure and character. By the time you reach the end of the course, you will have carried out a preliminary investigation of each, identified important questions about them and made a good deal of progress with some of the answers. As you work through the course developing statistical expertise, several of these data sets will be revisited and different questions addressed.

There are seven data set
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Chambers English Dictionary defines the word data as follows.

data, dātä,, n.pl. facts given, from which others may be inferred:—sing. da'tum(q.v.) …. [L. data, things given, pa.p. neut. pl. of dare, to give.]

You might prefer the definition given in the Shorter Oxford English Dictionary.

data, things given or granted; something known or assumed as fact, and made the basis of reasoning or calculation.

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There are more than 800 courses on OpenLearn for you to
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Now try the quiz and see if there are any areas you need to work on.

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Activity 33

The population of a village is 5481. Round this:

• (a) to the nearest thousand people;

• (b) to the nearest hundred people.

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Activity 27

Give the appropriate rounding for each of the values below:

• (a) Carpet floor area = 26.456 sq metres

• (b) Interest earned = £109.876 5439

• Author(s): The Open University When using a calculator many people have ‘blind
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Activity 21

Without using your calculator solve the following calculations.

• (a) 3 + 5 × 2 = ?

• (b) 12 − 6 + 6 = ?

• (c) 6 + (5 +
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You can use the same procedure for numbers less than one.

Example 4

In scientific work people deal with very small units of measurement. Suppose you read that the spacing between adjacent atoms in a solid was 0.000 002 456 84 metres. You could make the number more memorable
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After studying this course, you should be able to:

• round a given whole number to the nearest 10, 100, 1000 and so on

• round a decimal number to a given number of decimal places or significant figures

• use rounded numbers to find rough estimates for calculations

• use a calculator for decimal calculations involving +, −, × and ÷, giving the answer to a specified accuracy (e.g. decimal places or significant figures) and checking the ans
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• 1.   The condition ‘is equal to’ is a relation on any set of real numbers because, for any x, y in the set, the statement ‘x is equal to y’ is either definitely true or definitely false. This relation is usually denoted by the symbol =. For this relation, each real number in the set is related only to itself!

• 2.   The condition ‘is less than’ is a relation on any set of real numbers, and we usually
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In the last subsection we stated that, for any integer n ≥ 2, the set n satisfies the same rules for addition modulo n as the real numbers satisfy for ordinary addition. When it comes to multiplicat
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You have seen that the complex number x + iy corresponds to the point (x, y) in the complex plane. This correspondence enables us to give an alternative description of complex numbers, using so-called polar form. This form is particularly useful when we discuss properties related to multiplication and division of complex numbers.

[Image_Link]https://www.open.edu/openlearn/ocw/pluginfile.php/89651/mod_oucontent/ouconte
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Arithmetical operations on complex numbers are carried out as for real numbers, except that we replace i2 by −1 wherever it occurs.

Example 1

Let z1 = 1 + 2i and z<
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In OpenLearn course Diagrams, graphs and charts you saw how a scale is used on plans of houses and other structures. The scale makes it possible to take a length on the plan and calculate the correspond
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What is a volume? The word usually refers to the amount of three-dimensional space that an object occupies. It is commonly measured in cubic centimetres (cm3) or cubic metres (m3).

A closely related idea is capacity; this is used to specify the volume of liquid or gas that a container can actually hold. You might refer to the volume of a brick and the capacity of a jug – but not vice versa. Note that a container with a particular volume will not nec
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Look at the shapes below. The symmetry of the shape on the left and its relationship to the shape on the right can be thought of in two ways:

• Fold the left-hand shape along the central line. Then one side lies exactly on top of the other, and gives the shape on the right.

• Imagine a mirror placed along the central dotted line. The reflection in the mirror gives the other half of the shape.

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