JAMB Mathematics Past Questions & Answers - Page 76

376.

A school girl spends \(\frac{1}{4}\) of her pocket money on books and \(\frac{1}{3}\) on dress. What fraction remains?

A.

\(\frac{5}{6}\)

B.

\(\frac{7}{12}\)

C.

\(\frac{5}{12}\)

D.

\(\frac{1}{6}\)

Correct answer is C

let the girls' initial pocket money be whole(1)

\(\frac{1}{4}\) of 1 = books, \(\frac{1}{3}\)  of 1 = dress 

fraction of her money left = 1 - \(\frac{1}{4}\) - \(\frac{1}{3}\)

                                   =   \(\frac{5}{12}\)

 

 

377.

Solve for t in the equation \(\frac{3}{4}\)t + \(\frac{1}{3}\)(21 - t) = 11

A.

\(\frac{9}{13}\)

B.

\(\frac{7}{13}\)

C.

5

D.

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

Correct answer is D

\(\frac{3}{4}\) t + \(\frac{1}{3}\) (21 - t) = 11

  Multiply through by the LCM of 4 and 3 which is 12

  12 x(\(\frac{3}{4}\) t) + 12 x (\(\frac{1}{3}\) (21 - t)) = (11 x 12)

  9t + 4(21 - t) = 132

  9t + 84 - 4t = 132

  5t + 84 = 132

  5t = 132 - 84 = 48

  t = \(\frac{48}{5}\)

  t = 9 \(\frac{3}{5}\)

  Answer is D

378.

Find the value of x in the diagram

A.

10°

B.

28°

C.

36°

D.

40°

Correct answer is D

The diagram shows angles at a point, the total angle at a point is 360

  x - 10 + 4x - 50 + 2x + 3x + 20 = 360

  10x - 40 = 360

  10x = 360 + 40

  10x = 400

  x = \(\frac{400}{10}\)

  x = 40

379.

If y = 23\(_{five}\) + 101\(_{three}\) , find y, leaving your answer in base two

A.

1110

B.

10111

C.

11101

D.

111100

Correct answer is B

y = 23\(_{five}\) + 101\(_{three}\)

23\(_{five}\) = \(2 \times 5^1 + 3 \times 5^0\)

= 13\(_{ten}\)

101\(_{three}\) = \(1 \times 3^2 + 0 \times 3^1 + 1 \times 3^0\)

= 10\(_{ten}\)

y\(_{ten}\) = 13\(_{ten}\) + 10\(_{ten}\)

= 23\(_{ten}\)

= 10111\(_{two}\)

380.

If y = 23\(_{five}\) + 101\(_{three}\) , find y, leaving your answer in base two

A.

1110

B.

10111

C.

11101

D.

111100

Correct answer is B

y = 23\(_{five}\) + 101\(_{three}\)

23\(_{five}\) = \(2 \times 5^1 + 3 \times 5^0\)

= 13\(_{ten}\)

101\(_{three}\) = \(1 \times 3^2 + 0 \times 3^1 + 1 \times 3^0\)

= 10\(_{ten}\)

y\(_{ten}\) = 13\(_{ten}\) + 10\(_{ten}\)

= 23\(_{ten}\)

= 10111\(_{two}\)