JAMB Mathematics Past Questions & Answers - Page 398

1,986.

A woman buys 270 oranges for N1800.00 and sells at 5 for N40.00. What is her profit?

A.

N2,160.00

B.

N1, 620.00

C.

N630.00

D.

N360.00

Correct answer is D

C.P = N1800
S.P = (270/5) x 40 = N2160.00
Profit = S.P - C.P = N2160 - N1800 = N360.00

1,987.

Find (\(\frac{1}{0.06} \div \frac{1}{0.042}\))-1

A.

1.43

B.

1.53

C.

3.14

D.

4.42

Correct answer is A

\((\frac{1}{0.06} \div \frac{1}{0.042})^{-1}\)

= \((\frac{100}{6} \div \frac{1000}{42})^{-1}\)

= \((\frac{100}{6} \times \frac{42}{1000})^{-1}\)

= \((\frac{7}{10})^{-1}\)

= \(\frac{10}{7}\)

= 1.4285 \(\approxeq\) 1.43.

 

1,988.

In a class of 40 students, 32 offer mathematics, 24 offer Physics, and 4 offer neither Mathematics nor Physics. How many offer both Mathematics and Physics?

A.

20

B.

16

C.

8

D.

4

Correct answer is A

Using a venn diagram, let x = number who offer both Maths and Physics. So that (32-x) offer Maths and another (24-x) offer Physics.
(32-x) + (24-x) + (x) + (4 who offer neither) = 40
=> 60 - x = 40
=> -x = -20
Therefore x = 20.

1,989.

Simplify 213\(_4\) x 23\(_4\)

A.

103114

B.

103214

C.

122314

D.

132114

Correct answer is C

You can either multiply directly in base 4 or you can decide to convert to base 10 and do the multiplication and re-convert.

1,990.

Evaluate \(log_{\sqrt{2}}4+log_{\frac{1}{2}}16-log_{4}32\)

A.

-5.5

B.

-2.5

C.

2.5

D.

5.5

Correct answer is B

Note that if we set \(log_{\sqrt{2}}4 = x_{1}, \hspace{1mm}solving\hspace{1mm}gives\hspace{1mm}x_{1}=4\\if\hspace{1mm}log_{\frac{1}{2}}16 = x_{2}, \Rightarrow x_{2} = -4\\Also \hspace{1mm}for\hspace{1mm}log_{4}32 = x_{3} = 2.5\\Combining\hspace{1mm}results,\hspace{1mm}x_{1}+x_{2}+x_{3} = 4+(-4)-2.5=-2.5\)
Note that the solution has been separated to simplify solving difficulty due to different bases.