JAMB Mathematics Past Questions & Answers - Page 140

696.

In the figure, PQ\\SR, ST\\, ST\\RQ, PS = 7cm, PT = 7cm, SR = 4cm. Find the ratio of the area QRST to the area of PQRS.

A.

56.77

B.

56.105

C.

28:105

D.

28:49

E.

56:49

Correct answer is B

Area of QRST = 4 x 7 = 28

Area of PQRS = \(\frac{1}{2}\)(4 + 11) x 7

= \(\frac{7}{2}\) x \(\frac{15}{1}\)

= 28:52.5

= 56:105

697.

If PN is perpendicular to QR, find the value of tan x.

A.

\(\frac{5}{9}\)

B.

\(\frac{3}{5}\)

C.

\(\frac{3}{4}\)

D.

\(\frac{4}{3}\)

E.

\(\frac{4}{3}\)

Correct answer is B

By Pythagoras ON = 4

NR = 5

Tan x = \(\frac{3}{5}\)

698.

The area under the speed time graph given the total distance covered by car. What is the average velocity to two places of decimals?

A.

17.72 meter/sec.

B.

21.67 meters/sec

C.

2.5 meter/sec.

D.

20.45 meters/sec.

E.

13.33 meter/sec.

Correct answer is D

Time(sec) areas of the three sides are \(\frac{1}{2}\) x 2 x 20 = 20 x 2 = 40

\(\frac{1}{2}\) x 4 x 20 = 40

40 + 40 = 80

vel. = \(\frac{80}{4}\)

20 + 0.45 = 20.45 meter/sec.

699.

Find x in the diagram below.

A.

3\(\sqrt{3}\)

B.

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

C.

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

D.

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

Correct answer is B

\(\frac{x + 3}{sin 60^o}\) = \(\frac{x}{sin 306o}\)

3sin 30o = x sin 60o - x sin 30o

= x(sin 60o - sin 30o)

but sin 30o = \(\frac{1}{2}\)

sin 60o = \(\frac{3}{2}\) = \(\frac{3(\sqrt{3} - 1)}{\sqrt{3} + 1}\)

700.

PQ is parallel to RS. Calculate the value of x.

A.

20o

B.

40o

C.

60o

D.

80o

E.

100o

Correct answer is B

< D = 180o - 100v

= 80o (< on a str. line)

< s = 60o - alternate angle

x = 180o - (80o + 60o)

180o - 140o = 40o