NECO Mathematics Past Questions & Answers - Page 35

171.

An arc of a circle subtends an angle of 75° at the centre of the circle. If the diameter of the circle is 7cm, what Is the length of the arc? (take π = 3.142)

A.

4.58 cm

B.

8.02 cm

C.

16.04 cm

D.

32.08 cm

E.

34 cm

Correct answer is A

No explanation has been provided for this answer.

172.

Given that (3 - y) ÷ 2x = (6y + 7) ÷ (4x - 5), find the value of x when y = 2

A.

\(\frac{64}{5}\)

B.

6

C.

\(\frac{5}{34}\)

D.

\(\frac{-5}{34}\)

E.

\(\frac{-64}{5}\)

Correct answer is D

No explanation has been provided for this answer.

173.

If cos x = - \(\frac{5}{13}\) where 180° < X < 270°, what is the value of tan x -sin x ?

A.

\(\frac{111}{13}\)

B.

\(\frac{321}{65}\)

C.

-\(\frac{216}{65}\)

D.

\(\frac{112}{13}\)

E.

\(\frac{131}{65}\)

Correct answer is C

Given  cos x = - \(\frac{5}{13}\) 

→ adj = -5, hyp = 13 

Pythagoras' rule → hyp\(^2\) = Opp\(^2\) + adj\(^2\)

Opp\(^2\) = 13\(^2\) - [-5]\(^2\) → 169 - 25

Opp = √144 → 12

tan x = \(\frac{opp}{adj}\) → - \(\frac{12}{5}\) 

sin x = \(\frac{opp}{hyp}\) → \(\frac{12}{13}\) 

; tan x - sin x →  - \(\frac{12}{5}\) -  \(\frac{12}{13}\) 

=  - \(\frac{216}{65}\) 

 

174.

The mean age of 12 boys involved survey is 19 years, 3 months. lf the-age of one of the boys is 22 years, what is the mean age of the other-boys?

A.

10.5 years

B.

19.0 years

C.

35.4 years

D.

264.0 years

E.

423.5 years

Correct answer is B

No explanation has been provided for this answer.