WAEC Mathematics Past Questions & Answers - Page 285

1,421.

Given that 2p - m = 6 and 2p + 4m = 1, find the value of (4p + 3m).

A.

1

B.

3

C.

5

D.

7

E.

9

Correct answer is D

2p - m = 6 ... (i) 2p + 4m = 1 ... (ii) From (i), m = 2p - 6. 2p + 4(2p - 6) = 1 2p + 8p - 24 = 1 10p = 1 + 24 = 25 p = 2.5 m = 2(2.5) - 6 = 5 - 6 = -1 ∴ 4p + 3m = 4(2.5) + 3(-1) = 10 - 3 = 7

1,422.

Given that 2p - m = 6 and 2p + 4m = 1, find the value of (4p + 3m).

A.

1

B.

3

C.

5

D.

7

E.

9

Correct answer is D

2p - m = 6 ... (i) 2p + 4m = 1 ... (ii) From (i), m = 2p - 6. 2p + 4(2p - 6) = 1 2p + 8p - 24 = 1 10p = 1 + 24 = 25 p = 2.5 m = 2(2.5) - 6 = 5 - 6 = -1 ∴ 4p + 3m = 4(2.5) + 3(-1) = 10 - 3 = 7

1,423.

E = (integers \(\leq\) 20), P = (multiples of 3), Q = (multiples of 4), what are the elements of P'∩Q? 

A.

(12)

B.

(4, 8, 16, 20)

C.

(3, 6, 9, 15, 18)

D.

(1,2,5,7,10,11,13,17,19)

E.

(3, 4, 6, 8, 9, 12, 15, 16, 18, 20)

Correct answer is B

E = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}

P = {3, 6, 9, 12, 15, 18}

Q = {4, 8, 12, 16, 20}

P' = {1, 2, 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19, 20}

P' \(\cap\) Q = {4, 8, 16, 20}

1,424.

The sum of the 1st and 2nd terms of an A.P. is 4 and the 10th term is 19. Find the sum of the 5th and 6th terms.

A.

11

B.

20

C.

21

D.

22

E.

24

Correct answer is B

\(T_{n} = a + (n - 1) d\) (terms of an A.P)

\(T_{1} = a\)

\(T_{2} = a + d\)

\(T_{10} = a + 9d\)

\(a + a + d = 2a + d = 4 ... (i)\)

\(a + 9d = 19 ... (ii)\)

(ii) x 2: \(2a + 18d = 38 ... (iii)\)

(iii) - (i) : \(17d = 34 \implies d = 2\) 

\(2a + 2 = 4 \implies 2a = 2\)

\(a = 1\)

\(T_{5} + T_{6}\)

= \((a + 4d) + (a + 5d)\)

= \(2a + 9d\)

= \(2(1) + 9(2)\)

= 20

1,425.

A string is 4.8m. A boy measured it to be 4.95m. Find the percentage error.

A.

\( \frac{5}{16} \)%

B.

\(1\frac{5}{16} \)%

C.

\( 3\frac{1}{33} \)%

D.

\( 3\frac{1}{8} \)%

E.

25%

Correct answer is D

4.95m - 4.8m = 0.15m

\(\frac{0.15}{4.8} \times 100%\)

= \(\frac{25}{8}\)

= \(3\frac{1}{8}\)%