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Mathematics
WAEC / WASSCE 1998
Number and Numeration
A trader makes a loss of 15% when selling an article. Find the ratio, selling price : cost price
A
3:20
B
3:17
C
17:20
D
20:23
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #26377)
Mathematics
WAEC / WASSCE 1998
Number and Numeration
Solution
The side of a square is increased from 20cm to 21cm. Calculate the percentage increase in its area
A
2.5%
B
9.3%
C
10.0%
D
10.25%
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
old area = 20\(^2\) = 400
new area = 21\(^2\) = 441
% increase in area \(=\frac{41}{400}\times \frac{100}{1}\)
=10.25%
Source: Myschool Past Questions Archive (Record #26378)
Mathematics
WAEC / WASSCE 1998
Number and Numeration
Arrange in ascending order of magnitude \(26_8, 36_7, and 25_9\)
A
\(25_9 26_8 36_7\)
B
\(26_8 25_9 36_7\)
C
\(36_7 26_8 25_9\)
D
\(36_7 25_9 26_8\)
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #26379)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
If \(1011_2\) + \(X_7\) = \(25_{10}\), solve for X.
A
207
B
\(14_7\)
C
\(25_7\)
D
\(24_7\)
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
\(1011_2 + X_7 = 25_{10} = 1011_2 = 1 \times 2^3 + 0 \times 2^2 + 1 \times 2^1 + 1 \times 2^0\)
= 8 + 0 + 2 + 1
= \(11_{10}\)
\(X_7 = 25_{10} - 11_{10}\)
= \(14_{10}\)
\(\begin{array}{c|c}
7 & 14 \\ 7 & 2 R 0 \\ & 0 R 2
\end{array}\)
X = \(20_7\)
Source: Myschool Past Questions Archive (Record #30554)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
Evaluate [\(\frac{1}{0.03}\) \(\div\) \(\frac{1}{0.024}\)]-1 correct to 2 decimal places
A
3.76
B
1.25
C
0.94
D
0.75
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
[\(\frac{1}{0.03}\) + \(\frac{1}{0.024}\)]
= [\(\frac{1}{0.03 \times 0.024}\)]-1
= [\(\frac{0.024}{0.003}\)]-1
= \(\frac{0.03}{0.024}\)
= \(\frac{30}{24}\) = 1.25
Source: Myschool Past Questions Archive (Record #30559)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
If \(b^3\) = \(a^{-2}\) and \(c^{\frac{1}{3}}\) = \(a^\frac{1}{2}\)b, express c in terms of a
A
a-\(\frac{1}{2}\)
B
a\(\frac{1}{3}\)
C
a\(\frac{3}{2}\)
D
a\(\frac{2}{3}\)
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
\(c^{\frac{1}{3}}\) = \(a^{\frac{1}{2}}\)b
b = \(a^{-2}\) and \(c^{\frac{1}{3}}\) = \(a^{\frac{1}{2}}\)b
b = \(a^{-\frac{2}{3}}\)
\(c^{\frac{1}{3}}\) = \(a^{\frac{1}{2}}\) x \(a^{-\frac{2}{3}}\) = \(a^{-\frac{1}{6}}\)
take the cube of both sides
c = (\(a^{-\frac{1}{6}})^3\) = \(a^{-\frac{1}{2}}\)
Source: Myschool Past Questions Archive (Record #30603)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
Find the value of k if \(\frac{k}{\sqrt{3} + \sqrt{2}}\) = k\(\sqrt{3 - 2}\)
A
3
B
2
C
\(\sqrt{3}\)
D
\(\sqrt 2\)
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
\(\frac{k}{\sqrt{3} + \sqrt{2}}\) = k\(\sqrt{3 - 2}\)
\(\frac{k}{\sqrt{3} + \sqrt{2}}\) x \(\frac{\sqrt{3} - \sqrt{2}}{\sqrt{3} - \sqrt{2}}\) = k\(\sqrt{3 - 2}\)
K(\(\sqrt{3}\) - K\(\sqrt{2}\) ) = K\(\sqrt{3}\) - 2
K\(\sqrt{3}\) - K\(\sqrt{3}\) - K\(\sqrt{2}\) = - 2
- K\(\sqrt{2}\) = - 2
K = \(\frac{- 2}{- \sqrt{2}}\)
K = \(\frac{2}{\sqrt{2}}\) x \(\frac{\sqrt{2}}{\sqrt{2}}\)
K = \(\frac{2\sqrt{2}}{2}\) = \(\sqrt{2}\)
Source: Myschool Past Questions Archive (Record #30643)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
A market woman sells oil in cylindrical tins 10cm deep and 6cm in diameter at N15.00 each. If she bought a full cylindrical jug 18cm deep and 10cm in diameter for N50.00, how much did she make by selling all the oil?
A
N62.50
B
N35.00
C
N31.00
D
N25.00
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
V\(\pi\)r2h = \(\pi\)(3)2(10) = 90\(\pi\)cm3
V = \(\pi\)(5)2 x 18 = 450\(\pi\)cm3
No of volume = \(\frac{450\pi}{90\pi}\)
= 5
selling price = 5 x N15 = N75
profit = N75 - N50 = N25.00
Source: Myschool Past Questions Archive (Record #30649)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
Make \(\frac{a}{x}\) the subject of formula \(\frac{x + a}{x - a}\) = m
A
\(\frac{m - 1}{m + 1}\)
B
\(\frac{m + 1}{1 - m}\)
C
\(\frac{1 - m}{1 + m}\)
D
\(\frac{m + 1}{m - 1}\)
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
\(\frac{x + a}{x - a}\) = m
x + a = mx - ma
a + ma = mx - x
a(m + 1) = x(m - 1)
\(\frac{a}{x}\) = \(\frac{m - 1}{m + 1}\)
Source: Myschool Past Questions Archive (Record #30684)
Mathematics
UTME / JAMB 1998
Number and Numeration
Divide 2x\(^{3}\) + 11x\(^2\) + 17x + 6 by 2x + 1.
A
x2 + 5x + 6
B
2x2 + 5x - 6
C
2x2 + 5x + 6
D
x2 - 5x + 6
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #30687)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
Express in partial fractions \(\frac{11x + 2}{6x^2 - x - 1}\)
A
\(\frac{1}{3x - 1}\) + \(\frac{3}{2x + 1}\)
B
\(\frac{3}{3x + 1}\) - \(\frac{1}{2x - 1}\)
C
\(\frac{3}{3x + 1}\) - \(\frac{1}{2x - 1}\)
D
\(\frac{1}{3x + 1}\) + \(\frac{3}{2x - 1}\)
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
\(\frac{11x + 2}{6x^2 - x - 1}\) = \(\frac{11x + 2}{(3x + 1)(2x - 1)}\)
= \(\frac{A}{3x + 1}\) + \(\frac{B}{2x - 1}\)
11x + 2 = A(2x - 1) + B(3x + 1)
put x = \(\frac{1}{2}\)
\(\frac{15}{2} = \frac{5}{2}B\)
B = 3.
put x = \(-\frac{1}{3}\)
\(-\frac{5}{3} = \frac{-5}{3}\)A \(\implies\) A = 1
∴ \(\frac{11x +2}{6x^2 - x - 1}\) = \(\frac{1}{3x + 1}\) + \(\frac{3}{2x - 1}\)
Source: Myschool Past Questions Archive (Record #30696)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
If x is a positive real number, find the range of values for which \(\frac{1}{3x}\) + \(\frac{1}{2}\) > \(\frac{1}{4x}\)
A
x > -\(\frac{1}{6}\)
B
x > 0
C
0 < x < 4
D
0 < x < \(\frac{1}{6}\)
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
\(\frac{1}{3x}\) + \(\frac{1}{2}\) > \(\frac{1}{4x}\)
= \(\frac{2 + 3x}{6x}\) > \(\frac{1}{4x}\)
= 4x(2 + 3x) > 6x = 12x\(^2\) - 2x = 0
= 2x(6x - 1) > 0 = x(6x - 1) > 0
Case 1 (-, -) = x < 0, 6x -1 < 0
= x < 0, x < \(\frac{1}{6}\) = x < \(\frac{1}{6}\) (solution)
Case 2 (+, +) = x > 0, 6x -1 > 0 = x > 0, x > \(\frac{1}{6}\)
Combining solutions in cases(1) and (2)
= x > 0, x < \(\frac{1}{6}\) = 0 < x < \(\frac{1}{6}\)
Source: Myschool Past Questions Archive (Record #30704)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
The sum of the first three terms of a geometric progression is half its sum to infinity. Find the positive common ratio of the progression.
A
\(\frac{1}{4}\)
B
\(\frac{1}{\sqrt[3]{2}}\)
C
\(\frac{1}{\sqrt[3]{3}}\)
D
\(\frac{1}{\sqrt{2}}\)
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
Let the first term of the geometric progression (GP) be \( a \) and the common ratio be \( r \). The sum of the first three terms is: a + ar + ar\(^2\) = a(1 + r + r\(^2\))
\(S_3 = a(1 + r + r^2)\)
The sum to infinity is:
\(S_{\infty} = \frac{a}{1 - r}\)
But: \(S_3 = \frac{1}{2} S_{\infty}\)
Substituting the expressions gives:
\(a(1 + r + r^2) = \frac{1}{2} \cdot \frac{a}{1 - r}\)
Dividing by \( a \):
\(1 + r + r^2 = \frac{1}{2(1 - r)}\)
Cross-multiplying:
\(2(1 + r + r^2)(1 - r) = 1\)
Expanding and simplifying leads to:
\(2(1 - r^3) = 1\)
Thus: \(r^3 = \frac{1}{2}\)
Taking the cube root:
\(r = \sqrt[3]{\frac{1}{2}} = \frac{1}{\sqrt[3]{2}}\)
Therefore, the positive common ratio of the progression is:
\(\frac{1}{\sqrt[3]{2}}\).
Source: Myschool Past Questions Archive (Record #30712)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
The identity element with respect to the multiplication shown in the diagram below is \(\begin{array}{c|c} \otimes & p & p & r & s \\ \hline p & r & p & r & p
\\ q & p & q & r & s\\ r & r & r & r & r\\ s & q & s & r & q\end{array}\)
A
p
B
q
C
r
D
s
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
The identity element (e) under an operation, say \(\otimes\), is the element such that for any given element under the operation, say a,
\(a \otimes e = e \otimes a = a\)
From the table, q is the identity element.
\(p \otimes q = q \otimes p = p\)
Same as all through.
Source: Myschool Past Questions Archive (Record #30713)
Mathematics
UTME / JAMB 1998
Number and Numeration
Solution
The binary operation \(\ast\) is defined by x \(\ast\) y = xy - y - x for all real values x and y. If x \(\ast\) 3 = 2\(\ast\) x, find x
A
-1
B
4
C
1
D
5
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
x \(\ast\) y = xy - y - x, x \(\ast\) 3 = 3x - 3 - x = 2x - 3
2 \(\ast\) x = 2x - x - 2 = x - 2
∴ 2x - 3 = x - 2
x = -2 + 3
= 1
Source: Myschool Past Questions Archive (Record #30715)