JAMB Mathematics Past Questions & Answers - Page 186

926.

One interior angle of a convex hexagon is 170o and each of the remaining interior angles is equal to xo. Find x

A.

120o

B.

110o

C.

105o

D.

102o

E.

100o

Correct answer is B

An hexagon polygon is a six sided polygon

n = 6

sum of all interior angles of hexagon polygon will be (2n - 4) x 90o

= [2 x 6 - 4] x 90

= 720o

If one angle is 170o and each of the remaining five angles is 5xo

5xo + 170o = 720o

= 5x + 550

x = \(\frac{550}{5}\)

= 110o

927.

Factorize completely 81a\(^4\) - 16b\(^4\)

A.

(3a + 2b)(2a - 3b)(9a2 + 4b2)

B.

(3a - 2b)(2a - 3b)(4a2 - 9b2)

C.

(3a - 2b)(3a + 2b)(9a2 + 4b2)

D.

(6a - 2b)(8a - 3b)(4a3 - 9b2)

Correct answer is C

81a\(^4\) - 16b\(^4\) = (9a\(^2\))\(^2\) - (4b\(^2\))\(^2\)

= (9a\(^2\) + 4b\(^2\))(9a\(^2\) - 4b\(^2\))

N:B 9a\(^2\) - 4b\(^2\) = (3a - 2b)(3a + 2b)

928.

Without using tables find the numerical value of log749 + log7(\(\frac{1}{7}\))

A.

1

B.

2

C.

3

D.

7

E.

9

Correct answer is A

log749 + log7\(\frac{1}{7}\)

= log77

= 1

929.

If \((\frac{2}{3})^{m} (\frac{3}{4})^{n} = \frac{256}{729}\), find the values of m and n.

A.

m = 4, n = 2

B.

m = -4, n = -2

C.

m = -4, n =2

D.

m = 4, n = -2

E.

m = -2, n = 4

Correct answer is D

(\(\frac{2}{3}\))m (\(\frac{3}{4}\))n = \(\frac{256}{729}\)

\(\frac{2^m}{4^n}\) x \(\frac{3^n}{3^m}\) = \(\frac{2^{8}}{3^{6}}\)

\(2^{m} \div 2^{2n} = 2^{8}; 3^{n} \div 3^{m} = 3^{-6}\)

m - 2n = 8........(i)

-m + n = -6........(ii)

Solving the equations simultaneously

m = 4, n = -2

930.

If a rod of length 250cm is measured as 255cm long in error, what is the percentage error in the measurement?

A.

55

B.

10

C.

5

D.

4

E.

2

Correct answer is E

% error = \(\frac{\text{Actual error}}{\text{real value}}\) x 100

= \(\frac{5}{250}\) x 100

= 2%