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WAEC Mathematics Past Questions & Answers - Page 136

676.

A bucket holds 10 litres of water. How many buckets of water will fill a reservoir of size 8m x 7m x 5m.(1 litre = 1000cm3)`

A.

28

B.

280

C.

2800

D.

28000

Correct answer is D

No. of buckets of water = Capacity of reservoirCapacity of buckets

= 800×700×50010×1000

= 28000000010000

= 28000

677.

Each of the interior angles of a regular polygon is 140o. Calculate the sum of all the interior angles of the polygon

A.

1080o

B.

1260o

C.

1800o

D.

2160o

Correct answer is B

Each interior angle = 140

(n2)×180n=140

(n - 2) x 180 = 140n

150 - 360 = 140n

180m - 140n = 360

40n - 360

n = 36040

n = 9

Sum of all interior angles = (n - 2) x 180

= (9 - 2) x 180

= 7 x 180

= 1260

678.

If c and k are the roots of 6 - x - x2 = 0, find c + k

A.

2

B.

1

C.

-1

D.

-3

Correct answer is C

6 - x - x2 = 0

a = -1; b = -1; c = 6

Sum of roots = c + k = -ba

= (1)1

= -1

679.

If a positive integer, list the values of x which satisfy the equation 3x - 4 < 6 and x - 1 > 0

A.

{1, 2, 3}

B.

{2, 3}

C.

{2, 3, 4}

D.

{2, 3, 4, 5}

Correct answer is B

3x - 4 < 6 = 3x < 6 = 4

3x < 10

x < 103

x < 3.33 and x - 1 = 0

n > 1 = 1< x; since x is an integer, and 1 < x3.33

x = {2, 3}

680.

solve 2x+163x14 = 0

A.

1

B.

15

C.

-15

D.

-1

Correct answer is A

2x+163x14 = 0

4(2n+1)6(3x1)24 = 0

-10x + 10 = 0

-10x = -10

x = 1010

x = 1