Mathematics 2005 Jamb Examination

Mathematics 2005 Jamb Examination
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Question 1

Find the value of m if $13_m + 24_m = 41_m$

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If 13m + 24m = 41m
1 * m1 + 3 0 + 2 * m1 + 4 * m0 = 4 * m1 + 1 * m0
1 * m + 3 * 1 + 2 * m + 4 * 1 = 4 * m + 1 * 1
m + 3 + 2m + 4 = 4m + 1
3m + 7 = 4m + 1
4m -3m = 7 - 1
m = 6

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Question 2

If 3214 is divided by 234 and leaves a remainder r, what is the value of r?

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Convert to decimal:

$$ \begin{align*} 321_4 &= 3 \cdot 4^2 + 2 \cdot 4 + 1 = 48 + 8 + 1 = 57 \\ 23_4 &= 2 \cdot 4 + 3 = 11 \\ 57 \div 11 &= 5 \text{ remainder } 2 \\ r &= 2 \end{align*} $$

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Question 3

Simplify

\[3\dfrac{1}{2} - \left(2\dfrac{1}{3} \times 1\dfrac{1}{4} \right) + \dfrac{3}{5} \]

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First convert to improper fractions:

\[3\dfrac{1}{2} = \dfrac{7}{2}, \quad 2\dfrac{1}{3} = \dfrac{7}{3}, \quad 1\dfrac{1}{4} = \dfrac{5}{4}\]

Multiply: \[\dfrac{7}{3} \times \dfrac{5}{4} = \dfrac{35}{12}\]

Subtract and add: \[\dfrac{7}{2} - \dfrac{35}{12} + \dfrac{3}{5} = \dfrac{42}{12}-\dfrac{35}{12}+\dfrac{36}{60}\]\[ = \dfrac{7}{12}+\dfrac{36}{60} = 1\dfrac{11}{60}\]

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Question 4

If the interest on N150.00 for \(2\dfrac{1}{2}\) years is N4.50, find the interest on N250.00 for 6 months at the same rate

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Simple interest: \[SI = P \cdot r \cdot t\]

\[4.50 = 150 \cdot r \cdot 2.5 \implies r = \dfrac{4.5}{150 \cdot 2.5} = 0.012 = 1.2\%\]

Then for N250 for 0.5 years: \[SI = 250 \cdot 0.012 \cdot 0.5 = 1.5\]

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Question 5

Three boys shared some oranges. The first received 1/3 of the oranges and the second received 2/3 of the remaining. If the third boy received the remaining 12 oranges, how many oranges did they share

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Let x = the number of oranges
The 1st received 1/3 of x = 1/3x
∴Remainder = x - 1/3x = 2x/3
The 2nd received 2/3 of 2x/3 = 2/3 * 2x/3 = 4x/3
The 3rd received 12 oranges
∴1/3x + 4x/9 + 12 = x
(3x + 4x + 108)/9 = x
3x + 4x + 108 = 9x
7x + 108 = 9x
9x - 7x = 108
2x = 108
x = 54 oranges

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Question 6

Evaluate \[\dfrac{81^{\dfrac{3}{4}} - 27^{\dfrac{1}{3}}}{3 \times 2^3}\]
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Compute step by step:

\[81^{3/4} = (3^4)^{3/4} = 3^3 = 27\]

\[27^{1/3} = 3\]

Numerator: \(27 - 3 = 24\)

Denominator: \(3 \times 2^3 = 24\)

Therefore: \[\dfrac{24}{24} = 1\]

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Question 7

If \(\log_{10} 2 = 0.3010\) and \(\log_{10} 3 = 0.4771\), evaluate \(\log_{10} 4.5\)
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Use logarithm properties:

\[\log 4.5 = \log \dfrac{9}{2} = \log 9 - \log 2 = \log 3^2 - \log 2 = 2 \log 3 - \log 2\]

\[2 \cdot 0.4771 - 0.3010 = 0.9542 - 0.3010 = 0.6532\]

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Question 8

Simplify $$\dfrac{\sqrt{12} - \sqrt{3}}{\sqrt{12} + \sqrt{3}}$$

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Rationalize the denominator:

$$\dfrac{\sqrt{12} - \sqrt{3}}{\sqrt{12} + \sqrt{3}} \cdot \dfrac{\sqrt{12} - \sqrt{3}}{\sqrt{12} - \sqrt{3}}$$ $$= \dfrac{(\sqrt{12} - \sqrt{3})^2}{12 - 3}$$ $$= \dfrac{12 - 2\sqrt{36} + 3}{9} $$ $$= \dfrac{3}{9} $$ $$= \dfrac{1}{3}$$
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Question 9

The Venn diagram above shows a class of 40 students with the games they play. How many of the students play two games only?

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From the diagram, the numbers in the intersections (students playing exactly two games) sum to 15.

Two games played only = 5 + 7 + 3 = 15

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Question 10

If \(m = 3, p = -3, q = 7\) and \(r = \dfrac{5}{2}\), evaluate \(m(p+q+r)\)
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Compute step by step:

\[m(p+q+r) = 3(-3 + 7 + \dfrac{5}{2}) \]\[= 3(4 + \dfrac{5}{2}) \]\[= 3 \cdot \dfrac{13}{2} \]\[= \dfrac{39}{2} = 19.5\]

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Mathematics 2005 Jamb Examination
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