Mathematics Past Questions | West African Examinations Council (WAEC)

Question 21

mathematics-7

The graph is that of

For what value of will be negative? For what value of will

be negative?

Options

A)

B)

C)

D)

The correct answer is C.

Explanation:

The graph is that of










For what value of will be negative?

Question 22

mathematics-6

The diagram is a polygon. Find the largest of its interior angles.

Options

A) 300°

B) 100°

C) 120°

D) 150°

The correct answer is D.

Explanation:

Sum of interior angles = 360°
i.e 3x + 2x + 2x + x + 4x = 360°
12x = 360
x =


x = 30°
x + c = 180
30° + c = 180
c = 180 - 30
c = 150°

Question 23

Multiply

by

and leave your answers in standard form

Options

A)

B)

C)

D)

The correct answer is C.

Explanation:







Question 24

If

find

Options

A)

B)

C)

D)

The correct answer is B.

Explanation:








Question 25

In what number base is the addition 465 + 24 + 225 = 1050?

Options

A) ten

B) nine

C) eight

D) seven

The correct answer is D.

Question 26

Simplify

Options

A)

B)

C)

D)

The correct answer is D.

Explanation:


From numerator


From denominator




Question 27

If

evaluate

Options

A) 18

B) 56

C) 62

D) 80

The correct answer is C.

Explanation:








Question 28

If

, find

Options

A) -2

B) -1

C) 1

D) 2

The correct answer is D.

Explanation:














Question 29

A sales boy gave a change of

instead of

Calculate his percentage error

Options

A)

B)

C)

D)

The correct answer is B.

Explanation:

error
Error
Actual value
error =
=

Question 30

Four oranges sell for ₦x and three mangoes sell for ₦y. Olu bought 24 oranges and 12 mangoes. How much did he pay in terms of x and y?

Options

A) ₦(94x + 6y)

B) ₦(6x + 4y)

C) ₦(24x + 12y)

D) ₦(12x + 24y)

The correct answer is B.

Explanation:

4 oranges sell for ₦x, 1 orange will sell for


24 oranges will sell for: = ₦6x
3 mangoes sell for ₦y, 1 mango will sell for
12 mangoes will sell for = 4₦y
Total money paid: ₦6x + ₦4y = ₦(6x + 4y)

Question 31

Simplify:

Options

A)

B)

C)

D)

The correct answer is C.

Explanation:



Question 32

Solve the inequality:

Options

A)

B)

C)

D)

The correct answer is D.

Question 33

If

and evaluate:

Options

A)

B)

C)

D)

The correct answer is C.

Explanation:


Substitute and


Question 34

If

and and find

Options

A) 3

B) 2

C) 1

D) 5

The correct answer is A.

Explanation:

......(i)(multiply by 2)
......(ii)(multiply by 2)
......(iii)
.....(iv) add (iii) and (iv)

Substitute into equation (iii)





Question 35

Given that

, make

the subject of the equation

Options

A)

B)

C)

D)

The correct answer is D.

Explanation:

(Cross multiply)
(cross multiply)
3 cube root both side

Question 36

A chord is 2cm from the centre of a circle. If the radius of the circle is 5cm, find the length of the chord

Options

A) 2

cm

B)

cm

C) 2

cm

D)

cm

The correct answer is A.

Explanation:

From

OMQ find |MQ| by Pythagoras OQ2 = OM2 + MQ2
52 = 22 + MQ2
25 = 4 + MQ2
25 - 4 = MQ2
21 = MQ2
MQ2 = 21
MQ2 =
Length of chord

cm

Question 37

A cube and cuboid have the same base area. The volume of the cube is 64 cm3 while that of the cuboid is 80 cm3. Find the height of the cuboid

Options

A) 1 cm

B) 3 cm

C) 5 cm

D) 6 cm

The correct answer is A.

Question 38

If sin x =

and 0° x

90°, find the value of (cos x - tan x)

Options

A)

B)

C)

D)

The correct answer is C.

Explanation:

sin x =


x 90°, (cos x - tan x)
AC2 = AB2 + BC2
132 = 52 + BC2
169 - 25 + BC2
169 - 25 = BC2
144 = BC2
cos x = =
BC =
BC = 12
tan x =
BC = 12
cos x - tan x =

Question 39

An object is 6m away from the base of a mast. The angle of depression of the object from the top of the mast is 50°, Find, correct to 2 decimal places, the height of the mast

Options

A) 8.60m

B) 7.51m

C) 7.15m

D) 1.19m

The correct answer is C.

Explanation:

tan 50° =


h = 6 tan 50°
= 6 × 1.1917
= 7.1505
= 7.15

Question 40

The bearing of Y from X is 060° and the bearing of Z from Y = 060°. Find the bearing of X from Z

Options

A) 300°

B) 240°

C) 180°

D) 120°

The correct answer is B.


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