WAEC Past Questions and Answers - Page 1034

5,166.

In △PQR, \(\overline{PQ}\) = 5i - 2j and \(\overline{QR}\) = 4i + 3j. Find \(\overline{RP}\)

A.

-i - 5j

B.

-9 - j

C.

i + 5j

D.

-9i + j

Correct answer is A

\(\overline{PQ}\) = 5i - 2j;  \(\overline{QR}\) = 4i + 3j

 \(\overline{RP}\) = \(\overline{PQ}\) - \(\overline{QR}\)

= 5i - 2j - [4i + 3j] =  5i - 2j - 4i - 3j

= i - 5j

5,167.

Three forces, F\(_1\) (8N, 030°), F\(_\2) (10N, 150° ) and F\(_\3) ( KN, 240° )are in equilibrium. Find the value of N

A.

5√3

B.

6√2

C.

6√3

D.

9√3

Correct answer is C

No explanation has been provided for this answer.

5,168.

If 2y\(^2\) + 7 = 3y - xy, find \(\frac{dy}{dx}\)

A.

\(\frac{-y}{4x+y-3}\)

B.

\(\frac{y}{4x+y-3}\)

C.

\(\frac{-y}{4x+x-3}\)

D.

\(\frac{y}{4x+x-3}\)

Correct answer is D

2y\(^2\) + 7 = 3y - xy, find \(\frac{dy}{dx}\)

4y  \(\frac{dy}{dx}\) + 0 = 3 \(\frac{dy}{dx}\) - x  \(\frac{dy}{dx}\) + y

{4x+x-3}  \(\frac{dy}{dx}\) = y

= \(\frac{y}{4x+x-3}\)

5,169.

A fair die is tossed 60 times and the results are recorded in the table

Number of die 1 2 3 4 5 6
Frequency 15 10 14 2 8 11

Find the probability of obtaining a prime number.

A.

\(\frac{7}{30}\)

B.

\(\frac{1}{6}\)

C.

\(\frac{7}{15}\)

D.

\(\frac{8}{15}\)

Correct answer is D

Prime number in the experiment are 2,3 and 5 with frequencies 10,14 and 8

P(obtaining a prime number) = \(\frac{10+14+8}{60}\)

= \(\frac{32}{60}\) or \(\frac{8}{15}\)

5,170.

A body of mass 15kg is placed on a smooth plane which is inclined at 60° to the horizontal. If the box is at rest,

calculate the normal reaction to the plane. [ Take g = 10m/s\(^2\) ]

A.

129.9N

B.

75N

C.

60.0N

D.

7.5N

Correct answer is B

Let  the normal reaction be R

R = Wcosø = mgcosø

= 15 * 10cos 60°

= 150 * 0.5000

= 75N