Back to: MATHEMATICS JSS1
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In today’s class, we will be talking about estimation. Enjoy the class!
Estimation
Estimation (or estimating) is the process of finding an estimate, or approximation, which is a value that is usable for some purpose even if input data may be incomplete, uncertain, or unstable. The value is nonetheless usable because it is derived from the best information available
Example 1:
(a) The length of our classroom is 18 paces or 21 meters.
(b) The distance of this school from my house is
Some estimations are as follows:
(a) The length of our class is 18 paces or 21 meters
(b) A bottle of wine is 2 1/2 litres or 25 deciliters
(c) The distance of this school from my house is 3 kilometres.
(d) The mass of my friend is 20 kilograms.
(e) The weight of our teacher’s table is 500 grimes.
These are only estimating. People make estimates in units they are familiar with. There are many types of instruments used for confirming estimates.
A long time ago, people used the distance from a man’s elbow to the tip of his fingers, called ‘the cubit ‘to measure distances. Some use a man’s pace or foot. Some use the man’s hand palm stretch for measurements. These and many others are known as crude instruments
for measurement. They cannot give accurate answers. Later on, standard measurements were developed and used in most countries of the world. These include the meters and the kilometres for distances, the gram for mass or weight and the litre for capacity etc.
Example 2:
Estimate the length of your teacher’s table with a crude measurement.
Measure the top part of the teacher’s table with the hand palm stretch.
Various answers as 8,9. 10, 11, 12 palms.
Example 3:
Estimate the inside width of our classroom with cubit measure.
Various results such as 6, 7,7,8 or 10 cubits.
Average is about 8 cubits.
Estimation of distances
Like estimation of length, estimation of distances involves longer lengths.
Activity:
- Every student should estimate his or her height in meters and then measure the actual height.
- Estimate the length of the classroom and later find the accurate length.
- Let the students be in groups of five. Each group should go to the football field. Measure 10 meters and place a student every 10 meters apart.
- Name the different villages and towns near the Give a rough map and put the distances.
Example 1:
Estimate the following distances and then measure them to confirm your estimates.
(a) the length of the Assembly hall.
(b) the width of a football field.
(a) The length of the Assembly hall should involve a longer instrument of measurement, that is the meter, and not only the centimetre.
Estimation: 25 meters long.
Measurement: 21 meters 50 centimeters.
Written shortly as 21 m 50 cm
(b) Estimation: 60 meters.
Measurement: 65 meters.
Note: Assembly halls and football fields may vary from one institution to the other. There is no single correct answer.
Unit of Volume
Volume is the amount of space in a container or some given objects occupies. while capacity is usually referred to as the amount of space occupied by the liquid in a container.
The units of volume are derived from the units of length, and the basic units are the cubic centimetres for smaller containers and cubic meters for bigger ones.
The common units are:
1 000 cubic millimetres = l cubic centimetre
1 000 cubic centimetres = I cubic decimeter
1 000 cubic decimeters = l cubic meter
1 000 000 cubic centimeters = 1 cubic meter
The cubic millimetre is abbreviated as cu mm or mm³, cubic centimetre as cu cm or cm³ or cc, cubic meter as m³, cubic decimeter as dm³, and so on.
The basic unit of volume is the litre. Other units in Common use are the cubic centimetre (or cc) and the millilitre (or ml).
The conversion we can use are:
I liter = 1 000 milliliter (m)
1 liter = 1 000 cubic centimeter (cc)
1 centiliter (cl) = 1/10 liter
= 10 ml
I ml = l cc
The basic unit of capacity is the litre. A millilitre is abbreviated as ml. Centiliter as cl and cubic centimetre as cc.
Some common measures we can use for our estimation of containers are:
Cube of sugar, as l cu. cm or I cc. or 1 cm³
A box, which is 10 cm x 10 cm x 10 cm = 1000 ml
1 liter = 1 000 milliliters = 1 000 ml
1 liter = 1 000 cu. Cm = 1 000 cm³
I ml = 1 cc. Teaspoon = 5 ml
Tablespoon = 10 ml Normal bottle = liter.
Example
Estimate the content of:
(a) St. Louis packet of sugar.
(b) The volume of your classroom.
(c) Your teacup
(d) A kerosene tins.
(a) St. Louis packet of sugar is about
(4 x 6 x 3) cm³ = 72 cm³ or 70 cu cm
(b) Our classroom is about
(8 x 12 x 4) m³ = 384 m³ or 350 cu m
(c) Normal tea cup is about 15 tablespoons
i.e. (15 x 10) ml = 150 milliliters.
(d) A kerosene tin is about 2 liters.
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