# Mathematics 2020 Past Questions | WAEC

Study the following Mathematics past questions and answers for JAMB, WAEC NECO and Post-JAMB. Get prepared with official past questions and answers for upcoming examinations.

16. Two buses start from the same station at 9.00am and travel in opposite directions along the same straight road. The first bus travel at a speed of 72 km/h and the second at 48 km/h. At what time will they be 240km apart?

**A.**1:00 pm**B.**12:00 noon**C.**11:00 am**D.**10:00 am

**Correct Option: Answer is C**

17 Let t be the time

Then 72t + 48t = 240

= 120/120 x 240/120

t = 2hrs

9:00 + 2hrs = 11:00 am

**17. **A solid cuboid has a length of 7 cm, a width of 5 cm, and a height of 4 cm. Calculate its total surface area.

**A.**280 cm^{2}**B.**166 cm^{2}**C.**140 cm^{2}**D.**83 cm^{2}

**Correct Option: Answer is B**

**Total Surface Area of Cuboid, S = 2 (lw + wh + lh)**

**L= 7**

**W=5**

**H=4**

** **

**Therefore,**

= 2(7 x 5 + 5 x 4 + 7 x 4)

= 2(35 + 20 + 28)

= 2(83) = 166 cm^{2}

**18. **In the diagram, PQ//SR. Find the value of x.

**A.**34**B.**46**C.**57**D.**68

**Correct Option: Answer is B**

x + 68^{o} + 246^{o} = 360^{o}

x + 314^{o} = 360^{o}

x = 360^{o} – 314^{o}

x = 46^{o}

**19. **Find the equation of the line parallel to 2y = 3(x – 2) and passes through the point (2, 3)

**A.**y = 2/3x−3**B.**y = 2/3 x−2**C.**y = 2/3 x**D.**y = − 2/3x

**Correct Option: Answer is C**

**20.**The expression will be undefined when 5x+3/6x(x+1) equals

**A.**{0, 1}**B.**{0, -1}**C.**{-3, -11}**D.**{-3, 0}

**Correct Option: Answer is B**

6x(x + 1) = 0

When 6x = 0 and

x + 1 = 0

x = 0 and x = -1

(0, -1)

**21. **A man is five times as old as his son. In four years’ time, the product of their ages would be 340. If the son’s age is y, express the product of their ages in terms of y.

**A.**5y^{2}−16y−380=0**B.**5y^{2}−24y−380=0**C.**5y^{2}−16y−330=0**D.**5y^{2}−24y−324=0

**Correct Option: Answer is D**

Man = x, Son = y

x = 5y

(x + 4)(y + 4) = 350

(5y + 4)(y + 4) = 340

5y^{2 }+ 20y + 4y + 16 – 240 = 0

5y^{2} + 24y – 324 = 0

**21. **Simplify; \(\frac{a}{b} – \frac{a}{a} – \frac{c}{b}\)

**A.**\(\frac{a – b + c}{ab}\)**B.**\(\frac{ab – bc – ac}{ab}\)**C.**\(\frac{a^2 – b^2 + ac}{ab}\)**D.**\(\frac{a^2 – b^2 – ac}{ab}\)

**Correct Option: Answer is D**

\(\frac{a}{b} – \frac{b}{d} – \frac{c}{b}\)

\(\frac{a^2 – b^2- ac}{ab}\)

**23. **In the diagram, XYZ is an equilateral triangle of side 6cm and Y is the midpoint of XY¯. Find tan (< XZT)

**A.**-1/√3**B.**3/√2**C.**√3**D.**1/2

**Correct Option: Answer is A**

ZT = \(\sqrt{6^2 – 3^2}\)

ZT = \(\sqrt{27}\) = \(3\sqrt{3}\)

tan (< XZT) = \(\frac{3}{3\sqrt{3}}\)

= – \(\frac{1}{\sqrt{3}}\)

**24. **A fence 2.4 m tall, is 10m away from a tree of height 16m. Calculate the angle of elevation of the top of the tree from the top of the fence.

**A.**76.11^{o}**B.**53.67^{o}**C.**52.40^{o}**D.**51.32^{o}

**Correct Option: Answer is B**

Height = 16-2.4 =13.6

Tan θ = 13.6/10

= tan^{−}^{1}(1.36)

θ = 53.67^{o}

**25. **Fati buys milk at ₦x per tin sells each at a profit of ₦y. If she sells 10 tins of milk, how much does she receives from the sales?

**A.**₦(xy + 10)**B.**₦(x + 10y)**C.**₦(10x + y)**D.**₦10(x + y)

**Correct Option: Answer is D**

Tins sold =10 x ₦x

Profit = 10 x ₦y

₦10x + ₦10y

Therefore ₦10(x + y)

**26. **If tan y is positive and sin y is negative, in which quadrant would y lie?

**A.**First and third only**B.**First and second only**C.**Third only**D.**Second only

**Correct Option: Answer is C**

**27. **The dimension of a rectangular base of a right pyramid is 9 cm by 5cm. If the volume of the pyramid is 105 cm3, how high is the pyramid?

**A.**10cm**B.**6cm**C.**8cm**D.**7cm

**Correct Option: Answer is D**

Volume = 1/3 x 9 x 5 x h

105 = 1/3 x 9 x 5 x h

105/15=15h/15

h = 7cm

**28. **Each interior angle of a regular polygon is 168^{o}. Find the number of sides of the polygon

**A.**30**B.**36**C.**24**D.**18

**Correct Option: Answer is A**

Sum of exterior angles of any polygon = 360° Each exterior angle of a regular polygon **of n sides = 360° / n**.

Exterior angle = 180^{o} – 168^{o}

Number of sides = 360^{o}/12

**= 30**^{o}

^{o}

**29. **In the diagram, MN¯//PQ¯, < MNP = 2x, and < NPQ = (3x – 50)^{o}. Find the value of < NPQ

**A.**200^{o}**B.**150^{o}**C.**120^{o}**D.**90^{o}

**Correct Option: Answer is B**

2x = 3x – 50 alternate angle

50^{o} = 3x – 2x

50^{o} = x

< NPQ = (3x – 50)^{o}

= 3(500)^{o} – 50

= 150 – 50 = 150^{o}

**30. **The length of an arc of a circle of radius 3.5 cm is 1 19/36 Calculate, correct to the nearest degree , the angle substended by the centre of the circle. [Take π=22/7]

**A.**55^{o}**B.**36^{o}**C.**25^{o}**D.**22^{o}

**Correct Option: Answer is C**

L = \(\frac{\theta}{360^o}\) = 2\(\pi\)

\(\frac{55}{36} = \frac{\theta}{360^o} \times 2 \times \frac{22}{7} \times 3.5\)

\(\theta = \frac{360 \times 55 \times 44 \times 0.5}{3 \times 44 \times 0.5}\)

= \(\theta = 25^o\)