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Mathematics
UTME / JAMB 1999
Number and Numeration
Solution
If the minimum value of y = 1 + hx - 3x\(^2\) is 13, find h.
A
13
B
12
C
11
D
10
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
To find \( h \) for the function
\(y = 1 + hx - 3x^2\)
with a minimum value of 13:
1. The vertex \( x \) is given by
\(x = \frac{h}{6}\)
2. Substitute into the function:
\(y = 1 + \frac{h^2}{6} - 3\left(\frac{h}{6}\right)^2 = 1 + \frac{h^2}{6} - \frac{h^2}{12}\)
3. Combine terms:
\(y = 1 + \frac{2h^2}{12} - \frac{h^2}{12} = 1 + \frac{h^2}{12}\)
4. Set equal to 13:
\(1 + \frac{h^2}{12} = 13 \implies \frac{h^2}{12} = 12 \implies h^2 = 144 \implies h = 12 \text{ or } -12\)
\( h = 12 \) or \( h = -12 \).
Source: Myschool Past Questions Archive (Record #550)
Mathematics
UTME / JAMB 1999
Number and Numeration
Solution
Tope bought x oranges at N5.00 each and some mangoes at N4.00 each. If she bought twice as many mangoes as oranges and spent at least N65.00 and at most N130.00, find the range of the value of x.
A
4\(\leq\) x \(\leq\) 5
B
5\(\leq\) x \(\leq\) 8
C
5\(\leq\) x \(\leq\) 10
D
8\(\leq\) x \(\leq\) 10
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
Tope bought x oranges at ₦5.00 each and 2x mangoes at ₦4.00 each.
Total amount spent = \5x + 4(2x) = 5x + 8x = 13x
Given: ₦65.00 \le 13x \le ₦130.00
Divide through by 13:
5 \(\leq\) x \(\leq\) 10.
(or x = 5, 6, 7, 8, 9, 10)
Verification:
- When x = 5: 13 \times 5 = ₦65.00 (minimum)
- When x = 10: 13 \times 10 = ₦130.00 (maximum)
Source: Myschool Past Questions Archive (Record #10413)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Diagram
Solution
In the diagram above, |XR| = |RY| = |YZ| and ∠XRY = ∠YRZ = 62o, Calculate ∠XYZ
Attached Figure / Diagram
A
50o
B
62o
C
112o
D
115o
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
In triangle RXY, < RXY = < RYX (base angles of an isosceles triangle)
\(\implies\) 180^\circ - 62^\circ = 2 < RYX
118^\circ = 2 < RYX \(\implies\) < RYX = 59^\circ
In triangle RYZ, < RZY = 62^\circ (base angles of an isosceles triangle)
\(\therefore\) < RYZ = 180^\circ - (62^\circ + 62^\circ)
= 180^\circ - 124^\circ = 56^\circ
\(\therefore\) < XYZ = 56^\circ + 59^\circ
= 115^\circ
Source: WAEC / JAMB / NECO Classroom Archive (Record #26389)
Mathematics
UTME / JAMB 1999
Number and Numeration
Diagram
Solution
Find the value of l in the frustrum above
Attached Figure / Diagram
A
5cm
B
6cm
C
7cm
D
8cm
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
\DeltaABE and \DeltaACD are similar
therefore \(\frac{ x}{ x + 4} = \frac{3}{6}\)
6x = 3(x+4)
6x = 3x + 12
3x = 12
x = 4
In \DeltaACD; \(L^2\) = \((4+4)^2 + 6^2\)
= \(8^2 + 6^2\)
= 64 + 36
= 100
L = \(\sqrt{100}\)
= 10cm
In ABE, \((AE)^2 = 4^2 + 3^2\)
= 16 + 9
= 25
AE = 5cm
∴L = 10 - 5
= 5cm
Source: Myschool Past Questions Archive (Record #10418)
Mathematics
UTME / JAMB 1999
Number and Numeration
Diagram
Solution
The table above shows the frequency distribution of the ages (in years) of pupils in a certain secondary school. What percentage of the total number of pupils is over 15 years but less than 21 years?
Attached Figure / Diagram
A
35%
B
45%
C
50%
D
60%
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
% of those above 15 but less than 21 years
age = \(\frac{25}{50}\) x \(\frac{100}{1}\)
= 50%
Source: Myschool Past Questions Archive (Record #10420)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Solution
Simplify log\(_7\) 8 - log\(_7\) 2 + log\(_7\) 4.
A
0
B
\(2log_7 2\)
C
\(3log_7 2\)
D
\(4log_7 2\)
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
log\(_7\) 8 - log\(_7\) 2 + log\(_7\) 4
= log\(_7\) (8/2 x 4)
= log\(_7\) 16
= 4 log\(_7\) 2
Source: Myschool Past Questions Archive (Record #26381)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Solution
If \(K\sqrt{28}+\sqrt{63}-\sqrt{7}=0\), find K.
A
-2
B
-1
C
1
D
2
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
\(K\sqrt{28}+\sqrt{63}-\sqrt{7}=0\\
2K\sqrt{7}+3\sqrt{7}-\sqrt{7}=0\\
2K\sqrt{7}=-2\sqrt{7}\\
K=\frac{-2\sqrt{7}}{2\sqrt{7}}\\
K=-1\)
Source: Myschool Past Questions Archive (Record #26382)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Solution
From a set \(A = [3, \sqrt{2}, 2\sqrt{3}, \sqrt{9}, \sqrt{7}]\), a number is selected at random. Find the probability that is a rational number
A
\(\frac{1}{5}\)
B
\(\frac{2}{5}\)
C
\(\frac{3}{5}\)
D
\(\frac{4}{5}\)
medium Difficulty
Verified Correct Answer: Option B
Step-by-Step Mathematical Solution
\(A = {3, \sqrt{2}, 2\sqrt{3}, \sqrt{9}, \sqrt{7}}\)
n(A) = 5
Let the rational nos = R
n(R) = 2 (3, \(\sqrt{9}\))
P(R) = 2/5
Source: Myschool Past Questions Archive (Record #26383)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Solution
The pie chart illustrate the amount of private time a student spends in a week studying various subjects. use it to answer the question below
If he sends \(2\frac{1}{2}\) hours week on science, find the total number of hours he studies in a week
A
\(3\frac{1}{3}\) hours
B
5 hours
C
8 hours
D
12 hours
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
Let x represent the total number of hours spent per week
∴ \(\frac{75}{360} \times x = \frac{5}{2}\)
∴ x =\(\frac{360 \times 5}{725 \times 2}\) =12 hours
Source: Myschool Past Questions Archive (Record #26385)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Diagram
Solution
Calculate the value of Y in the diagram
Attached Figure / Diagram
A
18o
B
42o
C
48o
D
132o
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
x = 180^\circ - 123^\circ = 57^\circ
z = 180^\circ - 105^\circ = 75^\circ
y = 180^\circ - 57^\circ - 75^\circ = 48^\circ
Source: Myschool Past Questions Archive (Record #26391)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Solution
Given that m = -3 and n = 2 find the value of \(\frac{3n^2 - 2m^3}{m}\)
A
-22
B
-14
C
14
D
22
medium Difficulty
Verified Correct Answer: Option A
Step-by-Step Mathematical Solution
Given that m = -3, n = 2, the value of
\(\frac{3n^2 - 2m^3}{m}\)
\(\frac{3(2)^2 -2(-3)^3}{-3} = \frac{12+54}{-3}\) = -22
Source: Myschool Past Questions Archive (Record #26393)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Solution
Simplify \(\frac{2-18m^2}{1+3m}\)
A
\(2(1+3m)\)
B
\(2(1+3m^2)\)
C
\(2(1-3m)\)
D
\(2(1-3m^2)\)
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
\(\frac{2-18m^2}{1+3m}=\frac{2(1-(3m)^2)}{1+3m}\\
\frac{2(1-(3m)(1+3m)}{1+3m}=2(1-3m)\)
Source: Myschool Past Questions Archive (Record #26394)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Solution
If \(y = \sqrt{ax-b}\) express x in terms of y, a and b
A
\(x = \frac{y^2-b}{a}\)
B
\(x = \frac{y+b}{a}\)
C
\(x = \frac{y-b}{a}\)
D
\(x = \frac{y^2 + b}{a}\)
medium Difficulty
Verified Correct Answer: Option D
Step-by-Step Mathematical Solution
\(y = \sqrt{ax-b}\)
\(y^2 = ax-b\)
\(y^2 +b = ax\)
\(x = \frac{y^2 + b}{a}\)
Source: Myschool Past Questions Archive (Record #26395)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Solution
Given that \(81\times 2^{2n-2} = K, find \sqrt{K}\)
A
\(4.5\times 2^{n}\)
B
\(4.5\times 2^{2n}\)
C
\(9\times 2^{n-1}\)
D
\(9\times 2^{2n}\)
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
\(K = 81 \times 2^{2n - 2}\)
\(\sqrt{K} = \sqrt{81 \times 2^{2n - 2}}\)
= \(9 \times 2^{n - 1}\)
Source: Myschool Past Questions Archive (Record #26396)
Mathematics
WAEC / WASSCE 1999
Number and Numeration
Solution
Simplify \(\frac{4}{x+1}-\frac{3}{x-1}\)
A
\(\frac{x+7}{x^2 - 1}\)
B
\(\frac{x-7}{x^2 + 1}\)
C
\(\frac{x-7}{x^2 - 1}\)
D
\(\frac{x-11}{x^2 - 1}\)
medium Difficulty
Verified Correct Answer: Option C
Step-by-Step Mathematical Solution
\(\frac{4}{x+1}-\frac{3}{x-1} \\
=\frac{4x - 4 - 3x - 3}{(x+1)(x-1)}=\frac{x-7}{x^2 - 1}\)
Source: Myschool Past Questions Archive (Record #26397)