Q1. A right circular cone is placed over a cylinder of the same radius. Now the combined structure is painted on all sides. Then they are separated now the ratio of area painted on Cylinder to Cone is 3:1. What is the height of Cylinder if the height of Cone is 4 m and radius is 3 m?
A. 5 m
B. 6 m
C. 8 m
D. 10 m
Answer: B
Explanation:
Cylinder painted area = 2 [latex] \pi rh + \pi r² [/latex]
Cone painted area = [latex] \pi rl [/latex]
[latex] \frac {2h + r}{\sqrt {(r² + h1² )}} [/latex] = 3 : 1
h = 6
Q2. The diameter of Road Roller is 84 cm and its length is 150 cm. It takes 600 revolutions to level once on a particular road. Then what is the area of that road in m²?
A. 2376
B. 2476
C. 2496
D. 2516
Answer: A
Explanation:
Area
[latex]600 \times 2 \times \frac {22}{7} \times \frac {42}{100} \times \frac {150}{100} [/latex] = 2376
Q3. A smaller triangle is having three sides. Another big triangle is having sides exactly double the sides of the smaller triangle. Then what is the ratio of Area of a Smaller triangle to Area of the Bigger triangle?
A. 1 : 2
B. 2 : 1
C. 1 : 4
D. 4 : 1
Answer: C
Explanation:
Smaller triangle sides = a, b, c
Area = [latex] \sqrt {s (s - a) (s - b) (s - c)} [/latex]
s = [latex] \frac {a + b + c}{2} [/latex]
= [latex] \sqrt \frac {(a + b + c)(b + c - a) (a + c - b) (a + b - c)}{4} [/latex]
Bigger triangle = 2a, 2b, 2c
Area = [latex] \sqrt {(a + b + c)(b + c - a)(a + c - b)(a + b - c)} [/latex]
Ratio = 1 : 4
Q4. ABCD is a square of 20 m. What is the area of the least-sized square that can be inscribed in it with its vertices on the sides of ABCD?
A. 120 m²
B. 100 m²
C. 200 m²
D. 250 m²
Answer: C
Explanation:
It touches on midpoints on the sides of the square ABCD
Side = [latex] \sqrt {(10² +10²)} = \sqrt {200} [/latex]
Area = 200 m²
Q5. A hemispherical bowl of diameter 16cm is full of ice cream. Each student in a class is served exactly 4 scoops of ice cream. If the hemispherical scoop is having a radius of 2cm, then ice cream is served to how many students?
Answer: A
Explanation:
[latex] \frac {2}{3} \times \pi \times 8³ = n \times 4 \times \frac {2}{3} \pi 2³ [/latex]
n = 16