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JAMB Mathematics Past Questions & Answers - Page 41

201.

If sinx=45, find 1+cot2xcsc2x1.

A.

132

B.

259

C.

313

D.

411

Correct answer is B

sinx=oppHyp=45

52 = 42 + adj2

adj2 = 25 - 16 = 9

adj = 9 = 3

tanx=43

cotx=143=34

cot2x=(34)2=916

cscx=1sinx

= 145=54

csc2x=(54)2=2516

1+cot2xcsc2x1=1+91625161

= 2516÷916

= 259

202.

Calculate the volume of the regular three dimensional figure drawn above, where < ABC = 90° (a right- angled triangle).

A.

394 cm3

B.

425 cm3

C.

268 cm3

D.

540 cm3

Correct answer is D

|AC| = |DF| = 13 cm

Using Pythagoras theorem,

|AC|2 = |AB|2 + |BC|2

132 = 122 + |BC|2

|BC|2 = 169 - 144 = 25

|BC| = 25

= 5 cm

Volume of triangular prism = 12×base×length×height

= 12×5×12×18

= 540 cm3

203.

In the circle above, with centre O and radius 7 cm. Find the length of the arc AB, when < AOB = 57°

A.

5.32 cm

B.

4.39 cm

C.

7.33 cm

D.

6.97 cm

Correct answer is D

Length of arc = \frac{\theta}{360°} \times 2 \pi r

= \frac{57}{360} \times 2 \times \frac{22}{7} \times 7

= 6.97 cm

204.

The histogram above represents the number of candidates who did Further Mathematics examination in a school. How many candidates scored more than 40?

A.

100

B.

79

C.

150

D.

90

Correct answer is C

Number of students that scored above 40 = 55 + 45 + 30 + 15 + 5 = 150 students.

205.

Marks 1 2 3 4 5
Frequency 2y - 2 y - 1 3y - 4 3 - y 6 - 2y

The table above is the distribution of data with mean equals to 3. Find the value of y.

A.

5

B.

2

C.

3

D.

6

Correct answer is B

Marks (x) 1 2 3 4 5  
Frequency (f) 2y - 2 y - 1 3y - 4 3 - y 6 - 2y 3y + 2
fx 2y - 2 2y - 2 9y - 12 12 - 4y 30 - 10y 26 - y

Mean = \frac{\sum fx}{\sum f}

3 = \frac{26 - y}{3y + 2}

3(3y + 2) = 26 - y

9y + 6 = 26 - y

9y + y = 26 - 6

10y = 20 \implies y = 2