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Mathematics

Grade 5

Ordinary fractions and decimal fractions

Module 50

Solve problems in context

Activity 1:

To solve problems in context [lo 1.6.2]

1. Split up into groups of three. Find the solutions to these problems without using your pocket calculator.

  • A farmer wants to build a chicken coop with perches and needs the following timber for the job:
  • one plank of 4,3 m
  • one plank of 2,58 m
  • one plank of 3,26 m

What is the total length of all the planks that he needs?

1.2 In a certain residential area trees have to be cut down because they are touching the telephone wires. If they cut 0,259 m from the one tree, 1,5 m from the next and 2,93 m from the third tree, how many metres have been removed from the trees altogether?

1.3 Three buildings have to be painted. If one of the buildings is 16,8 m tall, the second one is 23,495 m tall and the third one is 46,77 m tall, how many metres have to be painted in all?

Activity 2:

To determine the equivalence and validity of different representations of the same problem through comparison and discussion [lo 2.6.3]

Addition of decimal fractions

1. In Activity 2.15 you had the opportunity of solving problems by using your own methods and techniques. Now you must work with a friend. Read the problem and then work through the different solutions of the various learners.

Three buildings are 58,2 m; 63,54 and 39,249 m high respectively. How high are they altogether?

1.1 I must calculate 58,2 + 63,54 + 39,249:

It is precisely the same as 58 + 2 10 size 12{ { {2} over {"10"} } } {} + 63 + 5 10 size 12{ { {5} over {"10"} } } {} + 4 100 size 12{ { {4} over {"100"} } } {} + 39 + 2 10 size 12{ { {2} over {"10"} } } {} + 4 100 size 12{ { {4} over {"100"} } } {} + 9 1000 size 12{ { {9} over {"1000"} } } {}

I add the whole numbers first: 58 + 63 + 39 = 160

Then I add all the tenths : 2 10 size 12{ { {2} over {"10"} } } {} + 5 10 size 12{ { {5} over {"10"} } } {} + 2 10 size 12{ { {2} over {"10"} } } {} = 9 10 size 12{ { {9} over {"10"} } } {}

Then I add the hundredths : 4 100 size 12{ { {4} over {"100"} } } {} + 4 100 size 12{ { {4} over {"100"} } } {} = 8 100 size 12{ { {8} over {"100"} } } {}

Lastly, I add everything together: 160 + 9 10 size 12{ { {9} over {"10"} } } {} + 8 100 size 12{ { {8} over {"100"} } } {} + 9 1000 size 12{ { {9} over {"1000"} } } {}

= 160 + 900 1000 size 12{ { {"900"} over {"1000"} } } {} + 80 1000 size 12{ { {"80"} over {"1000"} } } {} + 9 1000 size 12{ { {9} over {"1000"} } } {}

= 160 989 1000 size 12{ { {"989"} over {"1000"} } } {}

= 160,989

1.2 I use notation columns to calculate the sum of 58,2; 63,54 and 39,249:

T U t h th
5 8 2
6 3 5 4
3 9 2 5 5
16 0 9 8 9

The three buildings are 160,989 m high altogether.

1.3 I must calculate 58,2 + 63,54 + 39,249.

I do it exactly like a normal addition sum but I remember to keep the commas precisely underneath each other !

58,200

63,540

+ 39,249

160,989

2. Which method do you choose?

Why?

3. How do the first two methods compare with each other?

Activity 3:

To calculate by means of selection and through the use of suitable computations (additional) [lo 1.8]

1. Let us see how well you do on your own. Calculate the following without using a pocket calculator:

1.1: 3,247 + 117,9 + 36,58

1.2: 2,36 + 18,459 + 23,7

1.3: 5,742 + 87,62 + 49,136

1.4: 48,5 + 231,8 + 9,826

2. Try to do the following without any calculations: A farmer wants to fence his camp with wire but he only has loose pieces of wire. He has a piece of 2,5 m, another piece of 0,5 m and a third piece of 1,5m. How much wire does the farmer have altogether?

3. Explain to a friend how you calculated your answer!

4. Check all your answers of 1 and 2 with a calculator.

Brain-teaser!

Can you solve the following magic squares? You may use your calculator!

0,6 0,1
0,5
0,4

2,6
2,3
2 2,2

Activity 4:

To solve problems in context [lo 1.6.2]

1. Split up into groups of three. Your teacher will tell you which one of the problems below must be solved by your group. You will also be given the necessary paper to work on. Remember: no pocket calculators!

Questions & Answers

the diagram of the digestive system
Assiatu Reply
allimentary cannel
Ogenrwot
How does twins formed
William Reply
They formed in two ways first when one sperm and one egg are splited by mitosis or two sperm and two eggs join together
Oluwatobi
what is genetics
Josephine Reply
Genetics is the study of heredity
Misack
how does twins formed?
Misack
What is manual
Hassan Reply
discuss biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles
Joseph Reply
what is biology
Yousuf Reply
the study of living organisms and their interactions with one another and their environments
AI-Robot
the study of living organisms and their interactions with one another and their environment.
Wine
discuss the biological phenomenon and provide pieces of evidence to show that it was responsible for the formation of eukaryotic organelles in an essay form
Joseph Reply
what is the blood cells
Shaker Reply
list any five characteristics of the blood cells
Shaker
lack electricity and its more savely than electronic microscope because its naturally by using of light
Abdullahi Reply
advantage of electronic microscope is easily and clearly while disadvantage is dangerous because its electronic. advantage of light microscope is savely and naturally by sun while disadvantage is not easily,means its not sharp and not clear
Abdullahi
cell theory state that every organisms composed of one or more cell,cell is the basic unit of life
Abdullahi
is like gone fail us
DENG
cells is the basic structure and functions of all living things
Ramadan
What is classification
ISCONT Reply
is organisms that are similar into groups called tara
Yamosa
in what situation (s) would be the use of a scanning electron microscope be ideal and why?
Kenna Reply
A scanning electron microscope (SEM) is ideal for situations requiring high-resolution imaging of surfaces. It is commonly used in materials science, biology, and geology to examine the topography and composition of samples at a nanoscale level. SEM is particularly useful for studying fine details,
Hilary
cell is the building block of life.
Condoleezza Reply
what is cell divisoin?
Aron Reply
Diversity of living thing
ISCONT
what is cell division
Aron Reply
Cell division is the process by which a single cell divides into two or more daughter cells. It is a fundamental process in all living organisms and is essential for growth, development, and reproduction. Cell division can occur through either mitosis or meiosis.
AI-Robot
What is life?
Allison Reply
life is defined as any system capable of performing functions such as eating, metabolizing,excreting,breathing,moving,Growing,reproducing,and responding to external stimuli.
Mohamed
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Source:  OpenStax, Mathematics grade 5. OpenStax CNX. Sep 23, 2009 Download for free at http://cnx.org/content/col10994/1.3
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