Practical use of Mean, Mode and Median By: Below is Raw data collected. Their prices range from 6 lacs to 13 lacs.

General considerations The optical image An optical image may be regarded as the apparent reproduction of an object by a lens or mirror system, employing light as a carrier. An entire image is generally produced simultaneously, as by the lens in a camera, but images may also be generated sequentially by point-by-point scanning, as in a television Practical use of mean median and mode or in the radio transmission of pictures across long distances in space.

For this to be effective the image must be repeated as in motion pictures or scanned as in television at least 40 times a second to eliminate flicker or any appearance of intermittency. Historical background To the ancients, the processes of image formation were full of mystery.

Indeed, for a long time there was a great discussion as to whether, in vision, something moved from the object to the eye or whether something reached out from the eye to the object.

By the beginning of the 17th century, however, it was known that rays of light travel in straight lines, and in Johannes Keplera German astronomer, published a book on optics in which he postulated that an extended object could be regarded as a multitude of separate points, each point emitting rays of light in all directions.

The lens of the eye was not different from other lenses, and it formed an image of external objects on the retina, producing the sensation of vision. There are two main types of image to be considered: A real image is formed outside the system, where the emerging rays actually cross; such an image can be caught on a screen or piece of film and is the kind of image formed by a slide projector or in a camera.

A virtual imageon the other hand, is formed inside an instrument at the point where diverging rays would cross if they were extended backward into the instrument.

Such an image is formed in a microscope or telescope and can be seen by looking into the eyepiece. In the Italian physicist Vasco Ronchi went the other way and defined an image as any recognizable nonuniformity in the light distribution over a surface such as a screen or film; the sharper the image, the greater the degree of nonuniformity.

This concept is investigated fully under Optics and information theory below. Optics had progressed rapidly by the early years of the 19th century. Lenses of moderately good quality were being made for telescopes and microscopes, and in the great mathematician Carl Friedrich Gauss published his classical book on geometrical optics.

In it he expounded the concept of the focal length and cardinal points of a lens system and developed formulas for calculating the position and size of the image formed by a lens of given focal length. Since abouthowever, lens design has been almost entirely computerized, and the old methods of designing lenses by hand on a desk calculator are rapidly disappearing.

By the end of the 19th century numerous other workers had entered the field of geometrical optics, notably an English physicist, Lord Rayleigh John William Struttand a German physicist, Ernst Karl Abbe.

It is impossible to list all their accomplishments here. Since there has been a great resurgence in optics on the basis of information and communication theory, which is treated at length below.

Light rays, wavesand wavelets A single point of light, which may be a point in an extended object, emits light in the form of a continually expanding train of waves, spherical in shape and centred about the point of light.

It is, however, often much more convenient to regard an object point as emitting fans of rays, the rays being straight lines everywhere perpendicular to the waves. When the light beam is refracted by a lens or reflected by a mirror, the curvature of the waves is changed, and the angular divergence of the ray bundle is similarly changed in such a way that the rays remain everywhere perpendicular to the waves.

When aberrations are present, a convergent ray bundle does not shrink to a perfect point, and the emerging waves are then not truly spherical. In Christiaan Huygensa Dutch scientist, postulated that a light wave progresses because each point in it becomes the centre of a little wavelet travelling outward in all directions at the speed of lighteach new wave being merely the envelope of all these expanding wavelets.

When the wavelets reach the region outside the outermost rays of the light beam, they destroy each other by mutual interference wherever a crest of one wavelet falls upon a trough of another wavelet. Hence, in effect, no waves or wavelets are allowed to exist outside the geometrical light beam defined by the rays.

The normal destruction of one wavelet by another, which serves to restrict the light energy to the region of the rectilinear ray paths, however, breaks down when the light beam strikes an opaque edge, for the edge then cuts off some of the interfering wavelets, allowing others to exist, which diverge slightly into the shadow area.Before you can begin to understand statistics, you need to understand mean, median, and mode.

Without these three methods of calculation, it would be impossible to interpret much of the data we use . Although the mean is the most common type of average, the median can also be used to express the average of a group.

The median number in a group refers to the point where half the numbers are above the median and the other half are below it. Mean, median, mode, and range.

These are the most popular summarizing statistics used to describe a data set using one or several numbers. The mean, median and mode can all be called an "average" in certain literature, but using their proper technical names is recommended to avoid confusion.

Adding "arithmetic" also helps, since there is a geometric mean, a harmonic mean, a geometric median. Note from Mrs. Renz: My hope is that my students love math as much as I do! Play, learn, and enjoy math.

as you browse through this collection of my favorite third . Pre-algebra and algebra lessons, from negative numbers through pre-calculus.

Grouped by level of study. Lessons are practical in nature informal in tone, and contain many worked examples and warnings about problem areas and probable "trick" questions. The median is known as a measure of location; that is, it tells us where the data are.

As stated in, we do not need to know all the exact values to calculate the median; if we made the smallest value even smaller or the largest value even larger, it would not change the value of the median.

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