The area of a circle of radius 4cm is equal to (Take π = 3.142 )
A
10.3cm2
B
15.7cm2
C
50.3cm2
D
17.4cm2
CORRECT OPTION:
c
Area of a circle (A) = πr2
Radius = 4cm
π = 3.142
A = 3.142 × (4)2
= 3.142 × 16
= 50.272
A = 50.3cm2 (1dp)
6
The area of an ellipse is 132cm2.The length of its major axis is 14cm.Find the length of it minor axis
A
10.5cm
B
5cm
C
10cm
D
12cm
CORRECT OPTION:
d
The area of an ellipse (e) =πab/4
Let a rep. the length of its major axis = 14cm
Let b rep. the length of its minor axis = ?
π = 3.142
Area of an ellipse = 132cm2
132 = (π14 × b) ÷ 4
132 = (3.142 × 14b) ÷ 4
3.142 × 14b =132 × 4
b = (1324 × 4) ÷ (3.142 × 14)
= 528/43.988
= 12cm
The length of its minor axis (b) = 12cm
7
The volume of a cone (s) of height 6cm and base radius 5cm is
A
157cm3
B
155cm3
C
175cm3
D
145cm3
CORRECT OPTION:
a
V = ⅓ πr2 h
Volume of a cone (Vc) = ⅓ × 3.14 × (5)2 × 6
= 156.93
157cm3
8
The probability of an outcome A is 1/6 . The probability of the B outcome is 1/4 . If the probability of A or B or both is 1/12 . What is the probability of both outcomes A and B?