JAMB Mathematics Past Questions & Answers - Page 67

331.

Express 495g as a percentage of 16.5kg

A.

3%

B.

3 \(\frac{1}{3}\)%

C.

15%

D.

30%

Correct answer is A

The two numbers must be expressed in the same unit. To convert 495g to kg, it will be divided by 1000

  495g = \(\frac{495}{1000}\)

  = 0.495kg

  To express in percentage, 0.495 will be divided by 16.5 and then multiplied by 100

  % will be added to the answer \(\frac{0.4950}{16.5}\) x 100

  = 3%

332.

In the figure below, /MX/ = 8cm, /XN/ = 12cm, /NZ/ = 4cm and ∠ XMN = ∠ XZY. Calculate /YM/

A.

32cm

B.

24 cm

C.

16 cm

D.

12 cm

Correct answer is C

From the figure,

  ∠ XMN = ∠ XZY

  Angle X is common

  So, ∠ XNM = ∠ XYZ

  Then from the angle relationship

  \(\frac{XM}{XZ}\) = \(\frac{XN}{XY}\) = \(\frac{MN}{ZY}\)

  XM = 8, XZ = 12 + 4 = 16,

  XN = 12, XY = 8 + YM

  \(\frac{8}{16}\) = \(\frac{12}{(8 + YM) }\)

  Cross multiply

  8(8 + YM) = 192

  64 + 8YM = 192

  8YM = 128

  YM = \(\frac{128}{8}\)

  = 16cm

333.

In how many ways can the letters LEADER be arranged?

A.

72

B.

144

C.

360

D.

720

Correct answer is C

The word LEADER has 1L 2E 1A 1D and 1R making total of 6! \(\frac{6}{1!2!1!1!1!}\) = \(\frac{6!}{2!}\)

  = \(\frac{6 \times 5 \times 4 \times 3 \times 2 \times 1}{2 \times 1}\)

  = 360

334.

Integrate the expression 6x\(^2\) - 2x + 1

A.

3x\(^3\) - 2x\(^2\) + x + c

B.

2x\(^3\) - x\(^2\) + x + c

C.

2x\(^3\) – 3x\(^2\) + c

D.

x\(^3\) + x\(^2\) – x + c

Correct answer is B

6x\(^2\) - 2x + 1

\(\frac{6x^{2+1}}{2+1} - \frac{2x^{1+1}}{1+1}+ 1x = \frac{6x^3}{3} - \frac{2x^2}{2} + x\)

\(2x^3 - x^2 + x + c\)