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WAEC Mathematics Past Questions & Answers - Page 51

251.

Three exterior angles of a polygon are 30o, 40o and 60o. If the remaining exterior angles are 46o each, name the polygon.

A.

decagon

B.

nonagon

C.

octagon

D.

hexagon

Correct answer is C

Sum of all exterior angles is 360o

360o (30o - 40o)

360 - (130o)

230o

remaining is 46o = 23046 = 5

5 + 3 = 8 sides; Octagon

252.

Simplify; 2(6+22)23

A.

4

B.

3+4

C.

4 2

D.

43+4

Correct answer is A

2(6+22)23

12 + 2 x 2 - 23

2 3 - 2 3 + 4

= 4

253.

In what number base was the addition 1 + nn = 100, where n > 0, done?

A.

n - 1

B.

n + 1

C.

n

D.

n + 2

Correct answer is C

No explanation has been provided for this answer.

254.

The average age of a group of 25 girls is 10year. If one girl, aged 12 years and 4 months joins the group, find the new average age of the group

A.

10.1 years

B.

9.3 years

C.

8.7 years

D.

8 . 3 years

Correct answer is A

x = 10 ; 10 = x25

x = 250

x = 250+12.426

x = 10.09

x = 10.1 years

255.

Given that cos 30o = sin 60o = 32 and sin 30o = cos 60o = 12, evaluate tan60oq1tan30o

A.

32

B.

2 - 3

C.

3

D.

-2

Correct answer is C

Tan 60 = 3; Tan 30 = 1

tan60o11tan30o  = 31113 = 31313

= 311×313

= 311×33

= 3