If there is one prayer that you should pray/sing every day and every hour, it is the LORD's prayer (Our FATHER in Heaven prayer)
It is the most powerful prayer. A pure heart, a clean mind, and a clear conscience is necessary for it. - Samuel Dominic Chukwuemeka

For in GOD we live, and move, and have our being. - Acts 17:28

The Joy of a Teacher is the Success of his Students. - Samuel Chukwuemeka



Solved Examples: The Metric System of Measurements and Units

Samuel Dominic Chukwuemeka (SamDom For Peace) For ACT Students
The ACT is a timed exam...60 questions for 60 minutes
This implies that you have to solve each question in one minute.
Some questions will typically take less than a minute a solve.
Some questions will typically take more than a minute to solve.
The goal is to maximize your time. You use the time saved on those questions you solved in less than a minute, to solve the questions that will take more than a minute.
So, you should try to solve each question correctly and timely.
So, it is not just solving a question correctly, but solving it correctly on time.
Please ensure you attempt all ACT questions.
There is no negative penalty for any wrong answer.

For JAMB Students
Calculators are not allowed. So, the questions are solved in a way that does not require a calculator.

Solve all questions.
Use at least two methods as applicable.
State the measurement.
Show all work.


NOTE: Unless specified otherwise:
(1.) Use only the tables provided for you.
(2.) Please do not approximate intermediate calculations.
(3.) Please do not approximate final calculations. Leave your final answer as is.
Metric to Metric Conversions
Prefix Symbol Multiplication Factor
yocto y $10^{-24}$
zepto z $10^{-21}$
atto a $10^{-18}$
femto f $10^{-15}$
pico p $10^{-12}$
nano n $10^{-9}$
micro $\mu$ $10^{-6}$
milli m $10^{-3}$
centi c $10^{-2}$
deci d $10^{-1}$
deka da $10^1$
hecto h $10^2$
kilo K $10^3$
mega M $10^6$
giga G $10^9$
tera T $10^{12}$
peta P $10^{15}$
exa E $10^{18}$
zetta Z $10^{21}$
yotta Y $10^{24}$


(1.) Convert 16.27 meters to kilometers


Measurement is Length

$ \underline{First\:\:Method:\:\:Unity\:\:Fraction\:\:Method} \\[3ex] 16.27\:m\:\:to\:\:km \\[3ex] = 16.27\:m * \dfrac{.....km}{.....m} \\[5ex] = 16.27\:m * \dfrac{1\:km}{10^3\:m} \\[5ex] = 16.27\:m * \dfrac{1\:km}{1000\:m} \\[5ex] = \dfrac{16.27}{1000}\:km \\[5ex] = 0.01627\:km \\[3ex] \underline{Second\:\:Method:\:\:Proportional\:\:Reasoning\:\:Method} \\[3ex] 1\:km = 10^3\:m \\[3ex] 1\:km = 1000\:m \\[3ex] Let\:\:p = length\:\:of\:\:16.27\:m\:\:in\:\:km \\[3ex] $
$km$ $m$
$1$ $1000$
$p$ $16.27$

$ \dfrac{p}{1} = \dfrac{16.27}{1000} \\[5ex] p = 0.01627\:km \\[3ex] \therefore 16.27\:m = 0.01627\:km $
(2.) Convert 16.27 kilometers to meters


Measurement is Length

$ \underline{First\:\:Method:\:\:Unity\:\:Fraction\:\:Method} \\[3ex] 16.27\:km\:\:to\:\:m \\[3ex] = 16.27\:km * \dfrac{.....m}{.....km} \\[5ex] = 16.27\:km * \dfrac{10^3\:m}{1\:km} \\[5ex] = 16.27\:km * \dfrac{1000\:m}{1\:km} \\[5ex] = 16.27 * 1000 = 16270\:m \\[3ex] \underline{Second\:\:Method:\:\:Proportional\:\:Reasoning\:\:Method} \\[3ex] 1\:km = 10^3\:m \\[3ex] 1\:km = 1000\:m \\[3ex] Let\:\:p = length\:\:of\:\:16.27\:km\:\:in\:\:m \\[3ex] $
$km$ $m$
$1$ $1000$
$16.27$ $p$

$ \dfrac{p}{1000} = \dfrac{16.27}{1} \\[5ex] \dfrac{p}{1000} = 16.27 \\[5ex] Multiply\:\:both\:\:sides\:\:by\:\:1000 \\[3ex] 1000 * \dfrac{p}{1000} = 1000(16.27) \\[5ex] p = 16270\:m \\[3ex] \therefore 16.27\:km = 16270\:m $
(3.) Convert 25 dekagrams to decigrams


Measurement is Mass

$ \underline{First\:\:Method:\:\:Unity\:\:Fraction\:\:Method} \\[3ex] 25\:dag\:\:to\:\:dg \\[3ex] = 25\:dag * \dfrac{.....g}{.....dag} * \dfrac{.....dg}{.....g} \\[5ex] = 25\:dag * \dfrac{10\:g}{1\:dag} * \dfrac{1\:dg}{10^{-1}\:g} \\[5ex] = 25\:dag * \dfrac{10\:g}{1\:dag} * \dfrac{1\:dg}{0.1\:g} \\[5ex] = \dfrac{25 * 10}{0.1}\:dg \\[5ex] = \dfrac{250}{0.1}\:dg \\[5ex] = 2500\:dg \\[3ex] \underline{Third\:\:Method:\:\:Fast\:\:Proportional\:\:Reasoning\:\:Method} \\[3ex] 1\:dag = 10\:g \\[3ex] 1\:dg = 10^{-1}\:g \\[3ex] 1\:dg = 0.1\:g \\[3ex] $
$dag$ $g$ $dg$
$1$ $10$
$k$ $0.1$ $1$
$25$ $p$

$ Let\:\:k = length\:\:of\:\:1\:dg\:\:in\:\:dag \\[3ex] Let\:\:p = length\:\:of\:\:25\:dag\:\:in\:\:dg \\[3ex] First: \\[3ex] \dfrac{k}{1} = \dfrac{0.1}{10} \\[5ex] k = 0.01\:dag \\[3ex] Next: \\[3ex] \dfrac{p}{1} = \dfrac{25}{k} \\[5ex] p = \dfrac{25}{0.01} \\[5ex] p = 2500\:dg \\[3ex] \therefore 25\:dag = 2500\:dg $
(4.) Convert 25 decigrams to dekagrams


Measurement is Mass

$ \underline{First\:\:Method:\:\:Unity\:\:Fraction\:\:Method} \\[3ex] 25\:dg\:\:to\:\:dag \\[3ex] = 25\:dg * \dfrac{.....g}{.....dg} * \dfrac{.....dag}{.....g} \\[5ex] = 25\:dag * \dfrac{10^{-1}\:g}{1\:dg} * \dfrac{1\:dag}{10\:g} \\[5ex] = 25\:dag * \dfrac{0.1\:g}{1\:dg} * \dfrac{1\:dag}{10\:g} \\[5ex] = \dfrac{25 * 0.1}{10}\:dg \\[5ex] = \dfrac{2.5}{10}\:dag \\[5ex] = 0.25\:dag \\[3ex] \underline{Third\:\:Method:\:\:Fast\:\:Proportional\:\:Reasoning\:\:Method} \\[3ex] 1\:dg = 10^{-1}\:g \\[3ex] 1\:dg = 0.1\:g \\[3ex] 1\:dag = 10\:g \\[3ex] $
$dg$ $g$ $dag$
$1$ $0.1$ $a$
$10$ $1$
$25$ $c$

$ Let\:\:a = length\:\:of\:\:1\:dg\:\:in\:\:dag \\[3ex] Let\:\:p = length\:\:of\:\:25\:dg\:\:in\:\:dag \\[3ex] First: \\[3ex] \dfrac{a}{1} = \dfrac{0.1}{10} \\[5ex] a = 0.01\:dag \\[3ex] Next: \\[3ex] \dfrac{c}{a} = \dfrac{25}{1} \\[5ex] \dfrac{c}{0.01} = 25 \\[5ex] Multiply\:\:both\:\:sides\:\:by\:\: 0.01 \\[3ex] 0.01 * \dfrac{c}{0.01} = 0.01(25) \\[5ex] c = 0.25\:dag \\[3ex] \therefore 25\:dg = 0.25\:dag $
(5.)


(6.)


(7.) CSEC The scale on a map is $1:25000$
(i) Anderlin and Jersey are $31.8\:cm$ apart on the map.
Determine, in $km$, the actual distance between Anderlin and Jersey.

(ii) The actual distance between Clifton and James Town is $2.75\:km$
How many units apart are they on the map?


$ (i) \\[3ex] Scale = 1:25000 \\[3ex] 31.8\:cm \rightarrow ? \\[3ex] \underline{Second\:\:Method:\:\:Proportional\:\:Reasoning\:\:Method} \\[3ex] $
$Scale$ $Actual$
$1$ $25000$
$31.8$ $y$

$ \dfrac{1}{31.8} = \dfrac{25000}{y} \\[5ex] Cross\:\:Multiply \\[3ex] 1(y) = 31.8(25000) \\[3ex] y = 795000\:cm \\[3ex] \therefore 31.8\:cm = 795000\:cm \\[3ex] $ We need to convert this distance to $km$

$ \underline{First\:\:Method - Unity\:\:Fraction\:\:Method} \\[3ex] 795000\:cm\:\:to\:\:km \\[3ex] = 795000\:cm * \dfrac{0.01\:m}{1\:cm} * \dfrac{1\:km}{1000\:m} \\[5ex] = \dfrac{7950}{1000}\:km \\[5ex] = 7.95\:km \\[3ex] \underline{Second\:\:Method:\:\:Proportional\:\:Reasoning\:\:Method} \\[3ex] $
$cm$ $m$
$1$ $0.01$
$795000$ $x$

$ \dfrac{1}{795000} = \dfrac{0.01}{x} \\[5ex] Cross\:\:Multiply \\[3ex] 1(x) = 795000(0.01) \\[3ex] x = 7950\:m \\[3ex] $
$m$ $km$
$1000$ $1$
$7950$ $p$

$ \dfrac{1000}{7950} = \dfrac{1}{p} \\[5ex] Cross\:\:Multiply \\[3ex] 1000p = 7950(1) \\[3ex] 1000p = 7950 \\[3ex] p = \dfrac{7950}{1000} \\[5ex] p = 7.95\:km \\[3ex] (ii) \\[3ex] \underline{First\:\:Method - Unity\:\:Fraction\:\:Method} \\[3ex] 2.75\:km\:\:to\:\:cm \\[3ex] = 2.75\:km * \dfrac{1000\:m}{1\:km} * \dfrac{1\:cm}{0.01\:m} \\[5ex] = \dfrac{2750}{0.01}\:km \\[5ex] = 275000\:cm \\[3ex] \underline{Second\:\:Method:\:\:Proportional\:\:Reasoning\:\:Method} \\[3ex] $
$Scale$ $Actual$
$1$ $25000$
$d$ $275000$

$ \dfrac{1}{d} = \dfrac{25000}{275000} \\[5ex] \dfrac{25000}{275000} = \dfrac{5}{55} = \dfrac{1}{11} \\[5ex] \dfrac{1}{d} = \dfrac{1}{11} \\[5ex] Cross\:\:Multiply \\[3ex] d = 1(11) \\[3ex] d = 11\:cm \\[3ex] $ Clifton and James Town are $11\:cm$ apart on the map.
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