WAEC Past Questions and Answers - Page 2285

11,421.

M varies directly as n and inversely as the square of p. If M= 3 when n = 2 and p = 1, find M in terms of n and p.

A.

\(\frac{3n}{2p^2}\)

B.

\(\frac{2n}{3p^2}\)

C.

\(\frac{2n}{3p}\)

D.

\(\frac{3n^2}{2p^2}\)

Correct answer is A

M = \(\frac{nk}{p^2}\) 

k →  \(\frac{mp^2}{n}\) =  \(\frac{3x1^2}{2}\)

k =  \(\frac{3}{2}\)

:  m = \(\frac{3xn}{2p^2}\)

11,422.

Find the 17term of the Arithmetic Progression (A.P):-6,-1,4

A.

-91

B.

-86

C.

74

D.

79

Correct answer is C

common difference d =  -1 - [-6] → -1 + 6

d = 5; a = -6

T\(_n\) = a + (n-1)d

: T\(_{17}\) = -6 + (17 - 1) 5 

→ -6 + (16)5

→ -6 + 80 = 74

11,423.

A weaver bought a bundle of grass for $ 50.00 from which he made 8 mats. If each mat was sold for $ 15.00, find the percentage profit.

A.

240%

B.

140%

C.

120%

D.

40%

Correct answer is B

cost price = $50

Selling price = 15 * 8 = $120

percentage profit = \(\frac{sp-cp}{cp}\) * 100 →  \(\frac{120-50}{50}\) * 100

percentage profit = 70 * 2 → 140%

11,424.

If 4\(^{3x}\) = 16\(^{x+1}\), find the value of x 

A.

2

B.

3

C.

4

D.

5

Correct answer is A

4\(^{3x}\) = 4\(^{2(x+1)}\)

3x = 2x + 2

3x - 2x = 2

x = 2

11,425.

Evaluate 23 x 54 (mod 7)

A.

2

B.

3

C.

5

D.

6

Correct answer is B

23 x 54 = 1242

In mod 7; 

1242 ÷ 7 = 177 R 3 

Hence; 1242 ≡ 3