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WAEC Mathematics Past Questions & Answers - Page 194

966.

From the Venn diagram below, how many elements are in P∩Q?

A.

1

B.

2

C.

4

D.

6

Correct answer is B

P Q = {f, e} = 2

967.

If P=QR(1+3tR), make R the subject of the formula.

A.

R=3QtP2Q

B.

R=P23tQ+1

C.

R=P2+3tQ1

D.

R=P23QtQ

Correct answer is D

No explanation has been provided for this answer.

968.

In a ∆ XYZ, /YZ/ = 6cm YXZ = 60o and XYZ is a right angle. Calculate /XZ/in cm, leaving your answer in surd form

A.

2√3

B.

4√3

C.

6√3

D.

12√3

Correct answer is B

sinθ=opphypsin60o=|YZ||XZ|=6PPsin60o=6P=6sin60o=632=43

969.

Which of the following is/are not the interior angle(s) of a regular polygon?

I.108° 
II. 116°
III. 120°

A.

I only

B.

II only

C.

III only

D.

I and III only

Correct answer is B

Using the formula, (n - 2) \times 180° to get the sum of the interior angles. Then we can have

(n - 2) \times 180° = 108n ... (1)

(n - 2) \times 180° = 116n ... (2)

(n - 2) \times 180° = 120n ... (3)

Solving the above given equations, where n is not a positive integer then that angle is not the interior for a regular polygon.

(1): 180n - 360 = 108n \implies 72n = 360

 n = 5 (regular pentagon)

(2): 180n - 360 = 116n \implies 64n = 360

 n = 5.625

(3): 180n - 360 = 120n \implies 60n = 360

 n = 6 (regular hexagon)

Hence, 116° is not an angle of a regular polygon.

970.

If \frac{3^{(1-n)}}{9^{-2n}}=\frac{1}{9} find n

A.

-\frac{3}{2}

B.

\frac{1}{3}

C.

-1

D.

-3

Correct answer is C

\frac{3^{(1-n)}}{9^{-2n}}=\frac{1}{9}\\ 3^{1-n}\times 3^{-2(-2n)} = 3^{-2}\\ 1-n-2(-2n)= -2\\ 1-n+4n=-2\\ n=-1