2008 - JAMB Mathematics Past Questions and Answers - page 6

51
The cost of a kerosene per litre increases from N60 to N85. What is the percentage rate of increase?
A
42%
B
41%
C
40%
D
25%
correct option: a
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52
Simplify 16\(\frac{1}{2}\) x 4\(\frac{1}{2}\) x 27\(\frac{1}{3}\)
A
\(\frac{3}{8}\)
B
\(\frac{2}{3}\)
C
\(\frac{3}{4}\)
D
\(\frac{3}{2}\)
correct option: a

Simplify 16(\frac{1}{2}) x 4(\frac{1}{2}) x 27(\frac{1}{3})

= 16(\frac{1}{2}) x 4(\frac{1}{2}) x 27(\frac{1}{3})

= (\frac{1}{\sqrt{16}^1} \times \frac{1}{\sqrt{4}^1}) x (3(\sqrt{27}))1

= (\frac{1}{4}) x (\frac{1}{2}) x (\frac{3}{1})

= (\frac{3}{8})

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53
If \(logX^{\frac{1}{2}}\) 64 = 3, find the value of x.
A
4
B
16
C
32
D
64
correct option: b

(logX^{\frac{1}{2}}) 64 = 3, find the value of X

recall that X = 10p

log10X = P

64 = (X^{\frac{1}{2}})

43 = (X^{\frac{1}{2}})

(4^{3 \times \frac{1}{2}}) = (X^{\frac{1}{2} \times \frac{1}{3}})

4 = (X^{\frac{1}{2}})

(4)2 = (X^{\frac{1}{2} \times 2})

x = 16

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54
If \(\frac{1 + \sqrt{2}}{1 - \sqrt{2}}\) is expressed in the form x + y\(\sqrt{2}\). Find the values of x and y
A
(-3, -2)
B
(-2, 3)
C
(3, 2)
D
(2, -3)
correct option: a

(\frac{1 + \sqrt{2}}{1 - \sqrt{2}}) x (\frac{1 + \sqrt{2}}{1 + \sqrt{2}})

= (\frac{(1 + \sqrt{2}) (1 + \sqrt{2})}{(1 - \sqrt{2})(1 + \sqrt{2})})

= (\frac{1 + \sqrt{2} + \sqrt{2} + (\sqrt{2})^2}{1 + \sqrt{2} - \sqrt{2} - (\sqrt{2})^2})

= (\frac{1 + 2\sqrt{2} + \sqrt{2}}{1^2 - 2})

= (\frac{3 + 2\sqrt{2}}{-1})

-3 - 2(\sqrt{2}) = x + y(\sqrt{2})

x = -3, y = -2

= (-3, -2)

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55
if X = {n2 + 1 : n = 0, 2, 3} and y = {n + 1 : n = 2, 3, 4, 5}, find x ∩ y
A
{1, 3}
B
{5,10}
C
\(\Phi\)
D
(4, 6)
correct option: c

X = {n2 + 1 : n = 0, 2, 3}

y = {n + 1 : n = 2, 3, 4, 5}

find x ∩ y

x = (n2 + 1)(22 + 1)(32 + 1)

y = (2 + 1) (3 + 1)(5 + 1)

x = {1, 5, 10}

y = {3, 4, 6}

x ∩ y = (\Phi)

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56
Make Q the subject of the formula when L = \(\frac{4}{3}\) m\(\sqrt{PQ}\)
A
\(\frac{9L^2}{16m^2P}\)
B
\(\frac{3L}{4m \sqrt{P}}\)
C
\(\frac {\sqrt{3L}}{4mP}\)
D
\(\frac{3L^2}{16m^2P}\)
correct option: a

L = (\frac {4}{3}) m (\sqrt{PQ})

make Q the subject

(\frac {L}{1}) = (\frac {4}{3}) m (\sqrt{PQ})

3L = 4m (\sqrt{PQ})

Taking the square of both sides

(3L)2 = (4m (\sqrt{PQ}))

(\frac {9L^2}{16m^2P}) = (\frac {16m^2PQ}{16m^2P})

Q = (\frac {9L^2}{16m^2P})

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57
If 2x2 - kx - 12 is divisible by x - 4, find the value of k
A
4
B
5
C
6
D
7
correct option: b
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58
Factorize completely (4x + 3y)2 - (3x - 2y)2
A
(x + 5y)(7x + y)
B
(x + 5y)(7x - y)
C
(x - 5y)(7x + y)
D
(x - 5y)(7x -y)
correct option: a

(4x + 3y)2 - (3x - 2y)2

= 16x2 + 24xy + 9y - (9x2 - 12xy + 4y2)

= 7x2 + 36xy + 5y

= 7x2 + xy + 35xy + 5y2

= (7x2 + xy) + (35xy + 5y2)

= x(7x + y) + 5y(7x + y)

= (7x + y)(x + 5y)

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59
If x - 3 is directly proportional to the square of y and x = 5 when y = 2, find x when y = 6
A
30
B
21
C
16
D
12
correct option: b

x - 3 x y2

x - 3 = ky2

when x = 5, y = 2

5 - 3 = k(2)2

2 = 4k

k = (\frac{2}{4})

k = (\frac{1}{2})

Find x when y = 6

from x - 3 = ky2

x - 3 = (\frac{1}{2})ky2

x - 3 = (\frac{1}{2}) x 36

x - 3 = 18

x = 18 + 3

x = 21

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60
If p varies inverse as the square of q and p = 8 when q =4, find q when p = 32
A
\(\pm\)16
B
\(\pm\)8
C
\(\pm\)4
D
\(\pm\)2
correct option: d

P (\alpha) (\frac{1}{q^2})

p = (\frac{k}{q^2})

k = pq2

k = 8 x 42

k = 8 x 16 = 128

find k = pq2

q2 = (\frac{k}{p})

q = (\frac{k}{p})

q = (\frac{128}{32})

q = √4

q = (\pm)2

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