1994 - WAEC Mathematics Past Questions and Answers - page 2
A string is 4.8m. A boy measured it to be 4.95m. Find the percentage error.
4.95m - 4.8m = 0.15m
\(\frac{0.15}{4.8} \times 100%\)
= \(\frac{25}{8}\)
= \(3\frac{1}{8} %)
The sum of the 1st and 2nd terms of an A.P. is 4 and the 10th term is 19. Find the sum of the 5th and 6th terms.
\(T_{n} = a + (n - 1) d\) (terms of an A.P)
\(T_{1} = a\)
\(T_{2} = a + d\)
\(T_{10} = a + 9d\)
\(a + a + d = 2a + d = 4 ... (i)\)
\(a + 9d = 19 ... (ii)\)
(ii) x 2: \(2a + 18d = 38 ... (iii)\)
(iii) - (i) : \(17d = 34 \implies d = 2\)
\(2a + 2 = 4 \implies 2a = 2\)
\(a = 1\)
\(T_{5} + T_{6}\)
= \((a + 4d) + (a + 5d)\)
= \(2a + 9d\)
= \(2(1) + 9(2)\)
= 20
E = (integers \(\leq\) 20), P = (multiples of 3), Q = (multiples of 4), what are the elements of P'∩Q?
E = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}
P = {3, 6, 9, 12, 15, 18}
Q = {4, 8, 12, 16, 20}
P' = {1, 2, 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19, 20}
P' \(\cap\) Q = {4, 8, 16, 20}
Given that 2p - m = 6 and 2p + 4m = 1, find the value of (4p + 3m).
2p - m = 6 ... (i)
2p + 4m = 1 ... (ii)
From (i), m = 2p - 6.
2p + 4(2p - 6) = 1
2p + 8p - 24 = 1
10p = 1 + 24 = 25
p = 2.5
m = 2(2.5) - 6
= 5 - 6
= -1
\(\therefore\) 4p + 3m = 4(2.5) + 3(-1)
= 10 - 3
= 7
Which of the following is a point on the curve y = x\(^2\) - 4x + 7?
If 8x- 4 = 6x- 10, find the value of 5x,
8x - 4 = 6x - 10
8x - 6x = -10 + 4
2x = -6
x = -3
\(\therefore\) 5x = 5(-3)
= -15
For what value of x is the expression \(\frac{x^2 + 15x + 50}{x - 5}\) not defined ?
\(\frac{x^2 + 15x + 50}{x - 5}\)
It is undefined when x - 5 = 0.
That is at x = 5.
If x is positive, for what range of values of x is 4 + 3x < 10?
What is the equation of the line PQ?
The points P(-2, 3) and Q(2, 7) are on the line.
Gradient of the line = \(\frac{7 - 3}{2 - (-2)}\)
= \(\frac{4}{4}\)
= 1
y = x + b
To find the intercept, we have
7 = 2 + b or 3 = -2 + b.
Solving for b, we get b = 5.
\(\therefore\) The line is y = x + 5.