WAEC Mathematics Past Questions & Answers - Page 45

221.

Evaluate: 2\(\sqrt{28} - 3\sqrt{50} + \sqrt{72}\)  

A.

4\(\sqrt{7} - 21 \sqrt{2}\)

B.

4\(\sqrt{7} - 11 \sqrt{2}\)

C.

4\(\sqrt{7} - 9 \sqrt{2}\)

D.

4\(\sqrt{7} + \sqrt{2}\)

Correct answer is C

2\(\sqrt{28} - 3\sqrt{50} + \sqrt{22}\)

4\(\sqrt{7} - 15\sqrt{2} + 6\sqrt{2}\)

6\(\sqrt{7} - 9\sqrt{2}\)

222.

If 6, P, and 14 are consecutive terms in an Arithmetic Progression (AP), find the value of P.

A.

9

B.

10

C.

6

D.

8

Correct answer is B

6, p, 14

14 - p = p - 6 

14 + 6 = p - 6

14 + 6 = p + p

\(\frac{2p}{2}\)

= \(\frac{20}{2}\) 

p = 10

223.

If 23\(_y\) = 1111\(_{\text{two}}\), find the value of y

A.

4

B.

5

C.

6

D.

7

Correct answer is C

23\(_y\) = 1111\(_{\text{two}}\),

2 x y\(^1\) + 3 x y\(^0\) = 1 x 2\(^3\) + 1 x 2\(^1\) + 1 x 2\(^o\) 

2y + 3 = 8 + 4 + 2 + 1 

2y + 3 = 15 

\(\frac{2y}{2}\)

\(\frac{12}{2}\) 

y = 6

224.

Evaluate; \(\frac{\log_3 9 - \log_2 8}{\log_3 9}\) 

A.

-\(\frac{1}{3}\)

B.

\(\frac{1}{2}\)

C.

\(\frac{1}{3}\)

D.

-\(\frac{1}{2}\)

Correct answer is D

\(\frac{\log_3 9 - \log_2 8}{\log_3 9}\) 

= \(\frac{\log_3 3^2 - \log_2  2^3}{\log_3 3^2}\) 

= \(\frac{2 -3}{2}\)

= \(\frac{-1}{2}\) 

225.

If T = {prime numbers} and M = {odd numbers} are subsets of \(\mu\)  = {x : 0 < x ≤ 10} and x is an integer, find (T\(^{\prime}\) n M\(^{\prime}\)). 

A.

{4, 6, 8, 10}

B.

{1. 4, 6, 8, 10}

C.

{1, 2, 4, 6, 8, 10}

D.

{1, 2, 3, 5, 7, 8, 9}

Correct answer is A

T = {2, 3, 5, 7}

M = {1, 3, 5, 7, 9}

\(\mu\) = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} 

T\(^{\prime}\) = = {1, 4, 6, 8, 9, 10} 

M\(^{\prime}\) = {2, 4, 6, 8, 10} 

(T\(^{\prime}\) \(\cap\) M\(^{\prime}\)) = {4, 6, 8, 10}