2001 - WAEC Mathematics Past Questions and Answers - page 1
Which of the following correctly expresses 48 as a product of prime factors?
Evaluate \((20_{three})^2 - (11_{three})^2\) in base three
\((20_{three})^2 - (11_{three})^2\)
= \((20_{3} - 11_{3})(20_{3} + 11_{3})\)
= \((2_{3})(101_{3})\)
= \(202_{3}\)
log_{10}[5\times 20]\
log_{10}100\
log_{10}10^2\
2log_{10}10=2\)
In a class of 80 students, every students studies Economics or Geography or both. If 65 students study Economics and 50 study Geography, how many study both subjects?
Let c = no of students that offered both subjects
\(\therefore\) No of students offering Economics = 65 - c
No of students offering Geography = 50 - c
65 - c + c + 50 - c = 80
115 - c = 80
c = 35
35 students offer both Economics and Geography.
∴N = kM where k is a constant
N = 8 when M = 20
∴ 8 = k x 20
\(k = \frac{8}{20} = \frac{2}{5}\
∴ N = \frac{2}{5}M\
If N = 7\
∴ 7 = \frac{2}{5}M\
M = \frac{35}{2} = 17\frac{1}{2}\)
In a bag of oranges, the ratio of the good ones to the bad ones is 5:4. If the number of bad oranges in the bag is 36, how many oranges are there in the altogether?
Ratio of good ones to bad ones is 5:4; If 36 is bad;
∴ the good ones = \(\frac{5\times 36}{4}=45\) oranges.
The total number of oranges is 36 + 45 = 81.
=\frac{200-190}{200}\times \frac{100}{1}\
=\frac{10}{200}\times \frac{100}{1}\% = 5\%\)
\frac{27}{5}\times \frac{4}{9} \times \frac{3}{2}=3\frac{3}{5}
\)
The nth term of a sequence is \(2^{2n-1}\). Which term of the sequence is \(2^9?\)
\(T_{n} = 2^{2n - 1}\)
\(2^{2n - 1} = 2^9\)
\(2n - 1 = 9 \implies 2n = 9 + 1\)
\(2n = 10 \implies n = 5\)
The 5th term = 2\(^9\)