JAMB Mathematics Past Questions & Answers - Page 335

1,671.

The nth term of the progression \(\frac{4}{2}\), \(\frac{7}{3}\), \(\frac{10}{4}\), \(\frac{13}{5}\) is ...

A.

\(\frac{1 - 3n}{n + 1}\)

B.

\(\frac{3n + 1}{n + 1}\)

C.

\(\frac{3n + 1}{n - 1}\)

D.

\(\frac{3n - 1}{n + 1}\)

Correct answer is B

Using Tn = \(\frac{3n + 1}{n + 1}\),

T1 = \(\frac{3(1) + 1}{(1) + 1} = \frac{4}{2}\)

T2 = \(\frac{3(2) + 1}{(2) + 1} = \frac{7}{3}\)

T3 = \(\frac{3(3) + 1}{(3) + 1} = \frac{10}{4}\)

1,672.

Solve for x: |x - 2| < 3

A.

x < 5

B.

-2 < x < 3

C.

-1 < x < 5

D.

x < 1

Correct answer is C

|x - 2| < 3 implies -(x - 2) < 3 .... or .... +(x - 2) < 3 -x + 2 < 3 .... or .... x - 2 < 3 -x < 3 - 2 .... or .... x < 3 + 2 x > -1 .... or .... x < 5 combining the two inequalities results, we get; -1 < x < 5

1,673.

Evaluate 3(x + 2) > 6(x + 3)

A.

x < 4

B.

x > -4

C.

x < -4

D.

x > 4

Correct answer is C

3(x + 2) > 6(x + 3)

3x + 6 > 6x + 18

3x - 6x > 18 - 6

-3x > 12

x < -4

1,674.

If r varies inversely as the square root of s and t, how does s vary with r and t?

A.

s varies inversely as r and t2

B.

s varies inverely as r2 and t

C.

s varies directly as r2 and t2

D.

s varies directly as r and t

Correct answer is B

\(r \propto \frac{1}{\sqrt{s}}, r \propto \frac{1}{\sqrt{t}}\)

\(r \propto \frac{1}{\sqrt{s}}\) ..... (1)

\(r \propto \frac{1}{\sqrt{t}}\) ..... (2)

Combining (1) and (2), we get

\(r = \frac{k}{\sqrt{s} \times \sqrt{t}} = \frac{k}{\sqrt{st}}\)

This gives \(\sqrt{st} = \frac{k}{r}\)

By taking the square of both sides, we get

st = \(\frac{k^2}{r^2}\)

s = \(\frac{k^2}{r^{2}t}\)

1,675.

P varies jointly as m and u, and varies inversely as q. Given that p = 4, m = 3 and u = 2 and q = 1, find the value of p when m = 6, u = 4 and q =\(\frac{8}{5}\)

A.

12\(\frac{8}{5}\)

B.

15

C.

10

D.

28\(\frac{8}{5}\)

Correct answer is C

P \(\propto\) mu, p \(\propto \frac{1}{q}\)

p = muk ................ (1)

p = \(\frac{1}{q}k\).... (2)

Combining (1) and (2), we get

P = \(\frac{mu}{q}k\)

4 = \(\frac{m \times u}{1}k\)

giving k = \(\frac{4}{6} = \frac{2}{3}\)

So, P = \(\frac{mu}{q} \times \frac{2}{3} = \frac{2mu}{3q}\)

Hence, P = \(\frac{2 \times 6 \times 4}{3 \times \frac{8}{5}}\)

P = \(\frac{2 \times 6 \times 4 \times 5}{3 \times 8}\)

p = 10