1991 - WAEC Mathematics Past Questions and Answers - page 5
Mrs. Jones is expecting a baby. The probability that it will be a boy is 1/2 and probability that the baby will have blue eyes is 1/4. What is the probability that she will have a blue-eyed boy?
Which of the following about a rhombus may not be true?
The angles of a pentagon are x°, 2x°, (x + 60)°, (x + 10)°, (x -10)°. Find the value of x.
Sum of ∠s in a pentagon = (n - 2)180 = 540°
x° + 2x° + x° + 60° + x° + 10° + x° - 10° = 540°
6x° + 60° = 540°; x = 80°
In the diagram above, ∠PTQ = ∠URP = 25° and XPU = 4URP. Calculate ∠USQ.
Since < URP = 25°, then < XPU = 4 x 25° = 100°
\(\therefore\) < TPQ = 180° - 100° = 80°
\(\therefore\) < PQT = 180° - (80° + 25°) = 75°
< SQR = 75° - 25° = 50° (exterior angle = 2 opp interior angles)
\(\therefore\) < USQ = 180° - 50° = 130°
Users' Answers & Comments
Let x be the exterior angle; interior = 3x; but x + 3x = 180o
4x = 180o; x = 45
= (\frac{360}{45}) = 8
In the diagram above, O is the center of the circle, |SQ| = |QR| and ∠PQR = 68°. Calculate ∠PRS
From the figure, < PQR = 68°
\(\therefore\) < QRS = < QSR = \(\frac{180 - 68}{2}\) (base angles of an isos. triangle)
= 56°
\(\therefore\) < PRS = 90° - 56° = 34° (angles in a semi-circle)
Users' Answers & CommentsIn the diagram above, PQ and XY are two concentric arc; center O, the ratio of the length of the two arc is 1:3, find the ratio of the areas of the two sectors OPQ and OXY
Let the radius of the arc PQ = r and the radius of the arc XY = R.
Length of arc PQ = \(\frac{\theta}{360} \times 2\pi r = 1\)
Length of arc XY = \(\frac{\theta}{360} \times 2\pi R = 3\)
Ratio of the arc = \(\frac{r}{R} = \frac{360 \times 2\pi \theta}{2\pi \theta \times 360 \times 3}\)
= \(\frac{1}{3}\)
Ratio of their area = \((\frac{1}{3})^2 = \frac{1}{9}\)
= 1 : 9
Users' Answers & CommentsIn the diagram above , |AD| = 10cm, |DC| = 8cm and |CF| = 15cm. Which of the following is correct?