JAMB Mathematics Past Questions & Answers - Page 171

851.

List all integer values of x satisfying the inequality -1 < 2x - 5 \(\leq\) 5

A.

<2, 3, 4, 5

B.

3, 4, 5

C.

2, 3, 4

D.

3, 4

Correct answer is B

\(-1 < 2x - 5 \leq 5\)

\(\implies -1 + 5 < 2x - 5 + 5 \leq 5 + 5\)

\(4 < 2x \leq 10\)

\(\implies 2 < x \leq 5 \)

= 3, 4, 5.

852.

The median of the set of numbers 4, 9, 4, 13, 7, 14, 10, 17 is

A.

13

B.

7

C.

\(\frac{19}{2}\)

D.

\(\frac{39}{4}\)

E.

10

Correct answer is C

Rearranging in increasing order 4, 4, 7, 9, 10, 13, 14, 17, the

median = \(\frac{(9 + 10)}{2}\)

= \(\frac{19}{2}\)

853.

When a dealer sells a bicycle for N81 he makes a profit of 80%. What did he pay for the bicycle?

A.

N73

B.

N74.52

C.

N75

D.

N87.48

E.

N75.52

Correct answer is C

Profit = 8%

\(\therefore S.P = N81 = (100 + 8)% = 108%\)

\(108% = N81\)

\(100% = \frac{81}{108} \times 100\)

= \(\frac{8100}{108} = N75\)

854.

Rationalize the denominator of the given expression \(\frac{\sqrt{1 + a} - \sqrt{a}}{1 + a + \sqrt{a}}\)

A.

1 + 2a - 2\(\sqrt{a(1 + a)}\)

B.

\(\sqrt{1(1 + a)}\)

C.

2a - 2\(\sqrt{a(1 + a)}\)

D.

1 + 2a - 2\(\sqrt{a + b}\)

Correct answer is A

\(\frac{\sqrt{1 + a} - \sqrt{a}}{1 + a + \sqrt{a}}\) = \(\frac{\sqrt{1 + a} - \sqrt{a}}{\sqrt{1 + a} + \sqrt{a}}\) x \(\frac{\sqrt{1 + a} - \sqrt{a}}{\sqrt{1 + a} - \sqrt{a}}\)

= \(\frac{\sqrt{1 + a + a}}{1 + a - a}\)

= 2a + a(1 + a)

= 1 + 2a - 2\(\sqrt{a(1 + a)}\)

855.

Which of the following is NOT a factor of 12\(^{4}\) - 5\(^{4}\)?

A.

7

B.

13

C.

17

D.

49

E.

169

Correct answer is D

124 - 54 = (122)2 - (52)2

= (122 + 52) x (122 - 52)

(144 + 25)(144 - 25)

= (169)(119)

Factors of above 169, 17, 13, 7