Question 12 Marks
The wheel of the engine of a train $4 \frac{2}{7} m$ in circumference makes 7 revolutions in 3 seconds. Find the speed of the train in km per hour.
Answer
View full question & answer→$36 km / hr$
Questions
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Question 22 Marks
The diameter of a wheel is 1.26 m. How far will it travel in 500 revolutions ?
Answer
View full question & answer→1980 m
Question 32 Marks
AC and BD are two perpendicular diameters of a circle ABCD. Given that the area of the shaded portion is $308 cm ^2$calculate:
(i) the length of AC; and
(ii) the circumference of the circle.
(i) the length of AC; and
(ii) the circumference of the circle.
Answer
View full question & answer→(i) 28 cm
(ii) 88 cm
(ii) 88 cm
Question 42 Marks
The area enclosed between two concentric circles is $770 cm ^2$If the radius of the outer circle is 21 cm, calculate the radius of the inner circle.
Answer
View full question & answer→14 cm
[Hint. Let the radius of the inner circle be $(21-x) cm$. Then
$\begin{array}{l}
\pi(21)^2-\pi(21-x)^2=770 \Rightarrow x^2-42 x+245=0 \Rightarrow(x-35)(x-7)=0 . \\
\text { But }, x \neq 35 . \text { So }, x=7]\end{array}$
[Hint. Let the radius of the inner circle be $(21-x) cm$. Then
$\begin{array}{l}
\pi(21)^2-\pi(21-x)^2=770 \Rightarrow x^2-42 x+245=0 \Rightarrow(x-35)(x-7)=0 . \\
\text { But }, x \neq 35 . \text { So }, x=7]\end{array}$
Question 52 Marks
A wheel makes 1000 revolutions in covering a distance of 88 km. Find the radius of the wheel.
Answer
View full question & answer→14 m
Question 62 Marks
The diameter of a wheel is 1.26 m. How far will it travel in 500 revolutions ?
Answer
View full question & answer→1980 m
Question 72 Marks
The area enclosed between two concentric circles is 770$cm ^2$. If the radius of the outer circle is 21 cm, calculate the radius of the inner circle.
[Hint. Let the radius of the inner circle be (21 - x) cm. Then
$\begin{array}{l}\pi(21)^2-\pi(21-x)^2=770 \Rightarrow x^2-42 x+245=0 \Rightarrow(x-35)(x-7)=0 . \\ \text { But, } x \neq 35 . \text { So, } x=7]\end{array}$
[Hint. Let the radius of the inner circle be (21 - x) cm. Then
$\begin{array}{l}\pi(21)^2-\pi(21-x)^2=770 \Rightarrow x^2-42 x+245=0 \Rightarrow(x-35)(x-7)=0 . \\ \text { But, } x \neq 35 . \text { So, } x=7]\end{array}$
Answer
View full question & answer→14 cm