JAMB Mathematics Past Questions & Answers - Page 124

616.

The bar chart shows the distribution of marks in a class test. How many students took the test?

A.

15

B.

20

C.

25

D.

30

Correct answer is B

Number f students that took the test = \(\sum f\). Where f is the frequencies

= 2 + 5 + 0 + 3 + 4 + 0 + 0 + 2 + 3 + 1 + 2 = 20

617.

From the figure, calculate TH in centimeters

A.

\(\frac{5}{\sqrt{3} + 1}\)

B.

\(\frac{5}{\sqrt{3} - 1}\)

C.

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

D.

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

Correct answer is B

TH = tan 45o, TH = QH

\(\frac{TH}{5 + QH}\) = tan 30o

TH = (b + QH) tan 30o

QH = 56 (5 + QH) \(\frac{1}{\sqrt{3}}\)

QH(1 - \(\frac{1}{\sqrt{3}}\)) = \(\frac{5}{\sqrt{3}}\)

QH = \(\frac{5\sqrt{3}}{\sqrt{3}} - \frac{1}{\sqrt{3}}\)

= \(\frac{5}{\sqrt{3} - 1}\)

618.

In the figure, the area of the square of the square PQRS is 100cm2. If the ratio of the area of the square TUYS to the area of the area of the square XQVU is 1 : 16, Find YR

A.

6cm

B.

7cm

C.

8cm

D.

9cm

Correct answer is C

Since area of square PQRS = 100cm2

each lenght = 10cm

Also TUYS : XQVU = 1 : 16

lengths are in ratio 1 : 4, hence TU : UV = 1: 4

Let TU = x

UV = 1: 4

hence TV = x + 4x = 5x = 10cm

x = 2cm

TU = 2cm

UV = 8cm

But TU = SY and UV = YR

YR = 8cm

619.

In the figure, the line segment ST is tangent to two circles at S and T. O and Q are the centres of the circles wih OS = 5cm. QT = 2cm and OR = 14cm. Find ST

A.

7 \(\sqrt{3}\)cm

B.

12.9cm

C.

\(\sqrt{87}\)cm

D.

7cm

Correct answer is B

SQ2 + OS2 = OQ2 + 52 = 142

SQ2 = 142 - 52

196 - 25 = 171

ST2 + TQ2 = SQ2

ST2 + 22 = 171

ST2 = 171 - 4

= 167

ST = \(\sqrt{167}\)

= 12.92 = 12.9cm

620.

In the diagram, QPS = SPR, PR = 9cm. PQ = 4cm and QS = 3cm, find SR.

A.

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

B.

3\(\frac{3}{8}\)cm

C.

4\(\frac{3}{8}\)cm

D.

2\(\frac{3}{8}\)cm

Correct answer is A

Using angle bisector theorem: line PS bisects angle QPR

QS/QP = SR/PR

3/4 = SR/9

4SR = 27

SR = \(\frac{27}{4}\)

= 6\(\frac{3}{4}\)cm