2001 - WAEC Mathematics Past Questions and Answers - page 5

41
In the diagram, MN||PQ, |LM| = 3cm and |LP| = 4cm. If the area of ∆LMN is 18cm2, find the area of the quadrilateral MPQN
A
3cm2
B
6cm2
C
14cm2
D
24cm2
correct option: b
Using similar triangles
\(\frac{3}{16}=\frac{4}{x}\
x = \frac{18\times4}{3}=24cm^2\)
∴Area of quadrilateral MPQN
\(=24cm^2 - 18cm^2 = 6cm^2\)
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42

The diagram shows a triangular prism of length 7cm. The right - angled triangle PQR is a cross section of the prism |PR| = 5cm and |RQ| = 3cm. What is the area of the cross-section?

A
4 cm2
B
6cm2
C
15cm2
D
20cm2
correct option: b

In \(\Delta\) RQP, QR\(^2\) + QP\(^2\) = RP\(^2\)

3\(^2\) + QP\(^2\) = 5\(^2\)

QP\(^2} = 5\(^2\) - 3\(^2\)

QP = \(\sqrt{16}\)

= 4 cm 

\(\therefore\) Area = \(\frac{1}{2} \times base \times height\)

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

= 6 cm\(^2\)

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43

The diagram shows a triangular prism of length 7cm. The right - angled triangle PQR is a cross section of the prism |PR| = 5cm and |RQ| = 3cm. What is the volume of the prism?

A
28cm2
B
42cm2
C
70cm2
D
84cm2
correct option: b

Volume of prism = Area x height

In \(\Delta\) RQP, QR\(^2\) + QP\(^2\) = RP\(^2\)

3\(^2\) + QP\(^2\) = 5\(^2\)

QP\(^2} = 5\(^2\) - 3\(^2\)

QP = \(\sqrt{16}\)

= 4 cm 

\(\therefore\) Area = \(\frac{1}{2} \times base \times height\)

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

= 6 cm\(^2\)

Volume = 6 x 7

= 42 cm\(^3\)

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44

A solid cylinder of radius 7cm is 10 cm long. Find its total surface area.

A
\(70\pi cm^2\)
B
\(189\pi cm^2\)
C
\(210\pi cm^2\)
D
\(238\pi cm^2\)
correct option: d

S = \(2\pi r^2 + 2\pi rh\)

= \(2\pi r(r + h)\)

= \(2\pi (7) (7 + 10)\)

= \(238\pi cm^2\)

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45

PQRS is a trapezium in which |PS| = 9cm, |QR| = 15cm, |PQ| = \(2\sqrt{3}, \angle PQR = 90^o and \angle QRS = 30^o\). Calculate the area of the trapezium

A
\(24\sqrt{3} cm^2\)
B
\(36\sqrt{3} cm^2\)
C
\(42\sqrt{3} cm^2\)
D
\(72\sqrt{3} cm^2\)
correct option: a
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46

The variance of a given distribution is 25. What is the standard deviation?

A
125
B
75
C
25
D
5
correct option: d

S.D = \(\sqrt{Variance}\)

= \(\sqrt{25}\)

= 5

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47

Given that P = {b, d, e, f} and Q = {a, c, f, g} are subsets of the universal set U = {a,b, c, d, e, f, g}. Find P' ∩ Q

A
{a,c}
B
{a, c, d, g}
C
{c, d, g}
D
{a, c, g}
correct option: d

U = {a, b, c, d, e, f, g}

P = {b, d, e, f}

Q = {a, c, f, g}

P' = {a, c, g}

P' \(\cap\) Q = {a, c, g}

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48

What is the length of \(\bar{RP}\)?

A
6
B
5
C
3
D
2
correct option: b

\(\bar{RP} = 3 - (-2)\)

= 5

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49

The number line represents

A
0 > x \(\geq\) -7
B
-7 \(\leq\) x < -1
C
-7 < x \(\leq\) -1
D
-7 < x < -1
correct option: c
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