Mathematics 2018 Jamb Examination
Mathematics 2018 Jamb Examination
Question 1
In a class of 40 students, 32 offer Mathematics, 24 offer Physics and 4 offer neither Mathematics nor Physics. How many offer both Mathematics and Physics?
First, find the number of students who offer at least one of the two subjects:
\[ n(M \cup P) = \text{Total} - \text{Neither} = 40 - 4 = 36 \]
Using the set formula \( n(M \cup P) = n(M) + n(P) - n(M \cap P) \):
\[ 36 = 32 + 24 - n(M \cap P) \]
\[ 36 = 56 - n(M \cap P) \implies n(M \cap P) = 56 - 36 = 20 \]
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Question 2
Find the values of \( x \) for which \(\displaystyle \frac{x+2}{4} - \frac{2x - 3}{3} < 4 \)
Multiply the entire inequality by the LCM of 4 and 3, which is 12, to clear the fractions: \[ 3(x + 2) - 4(2x - 3) < 48 \] \[ 3x + 6 - 8x + 12 < 48 \] \[ -5x + 18 < 48 \] \[ -5x < 30 \] When dividing by a negative number, the inequality sign reverses: \[ x > \frac{30}{-5} \implies x > -6 \]
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Question 3

The pie chart shows the monthly expenditure of a public servant. The monthly expenditure on housing is twice that of school fees. How much does the worker spend on housing if his monthly income is N7200?
First, find the total degrees remaining for Housing and School Fees:
\[ 360^\circ - (90^\circ + 120^\circ) = 360^\circ - 210^\circ = 150^\circ \]
Let the angle for School Fees be \( x \) and Housing be \( 2x \):
\[ x + 2x = 150^\circ \implies 3x = 150^\circ \implies x = 50^\circ \]
So, the angle for Housing is \( 2(50^\circ) = 100^\circ \).
\[ \text{Expenditure} = \frac{100}{360} \times 7200 = 100 \times 20 = 2000 \]
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Question 4
A trader realises \( 10x - x^2 \) Naira profit from the sale of \( x \) bags of corn. How many bags will give him the maximum profit?
To find the maximum profit, differentiate the profit function \( P = 10x - x^2 \) and set it to zero:
\[ \frac{dP}{dx} = 10 - 2x \]
\[ 10 - 2x = 0 \implies 2x = 10 \implies x = 5 \]
Alternatively, for a quadratic \( ax^2 + bx + c \), maximum occurs at \( x = -b/2a \):
\[ x = \frac{-10}{2(-1)} = 5 \]
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Question 5
If \( y = 23_{\text{five}} + 101_{\text{three}} \), find \( y \), leaving your answer in base two
\[ 23_{5} = (2 \times 5^{1}) + (3 \times 5^{0}) = 10 + 3 = 13 \] \[ 101_{3} = (1 \times 3^{2}) + (0 \times 3^{1}) + (1 \times 3^{0}) = 9 + 0 + 1 = 10 \] \[ y = 13 + 10 = 23_{10} \] Now convert \(23_{10}\) to base two. \[ \begin{array}{c|c} \text{Division} & \text{Remainder} \\ \hline 23 \div 2 = 11 & 1 \\ 11 \div 2 = 5 & 1 \\ 5 \div 2 = 2 & 1 \\ 2 \div 2 = 1 & 0 \\ 1 \div 2 = 0 & 1 \end{array} \uparrow \] \[ 23_{10} = 10111_{2} \]
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Question 6

Find the value of \( x \) in the diagram
The sum of angles at a point is \(360^\circ\). \[ (x - 10) + (4x - 50) + 3x + (2x + 20) = 360 \] \[ x - 10 + 4x - 50 + 3x + 2x + 20 = 360 \] \[ 10x - 40 = 360 \] \[ 10x = 400 \] \[ x = 40 \]
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Question 7
Solve for \( t \) in the equation \( \frac{3}{4}t + \frac{1}{3}(21 - t) = 11 \)
Multiply the entire equation by the LCM of 4 and 3, which is 12:
\[ 12 \left( \frac{3}{4}t \right) + 12 \left( \frac{1}{3}(21 - t) \right) = 12(11) \]
\[ 9t + 4(21 - t) = 132 \]
\[ 9t + 84 - 4t = 132 \]
\[ 5t = 132 - 84 \]
\[ 5t = 48 \implies t = \frac{48}{5} = 9\frac{3}{5} \]
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Question 8
A school girl spends \( \frac{1}{4} \) of her pocket money on books and \( \frac{1}{3} \) on dress. What fraction remains?
First, find the total fraction spent:
\[ \frac{1}{4} + \frac{1}{3} = \frac{3 + 4}{12} = \frac{7}{12} \]
To find the remaining fraction, subtract the amount spent from the whole (1):
\[ 1 - \frac{7}{12} = \frac{12 - 7}{12} = \frac{5}{12} \]
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Question 9
If \( \frac{x}{a + 1} + \frac{y}{b} = 1 \). Make \( y \) the subject of the relation.
Isolate the term containing \( y \):
\[ \frac{y}{b} = 1 - \frac{x}{a + 1} \]
Combine the right side into a single fraction:
\[ \frac{y}{b} = \frac{(a + 1) - x}{a + 1} \]
Multiply both sides by \( b \):
\[ y = \frac{b(a + 1 - x)}{a + 1} \]
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Question 10
Calculate the total surface area of a cupboard which measures 12cm by 10cm by 8cm
Β The total surface area (TSA) of a cuboid is given by \( 2(lw + lh + wh) \): \[ TSA = 2(12 \times 10 + 12 \times 8 + 10 \times 8) \] \[ TSA = 2(120 + 96 + 80) \] \[ TSA = 2(296) = 592\text{cm}^2 \]
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